364 research outputs found
Impact of surface phenomena on direct bulk flexoelectric effect in finite samples
In the framework of a continuum theory, it is shown that the direct
flexoelectric response of a finite sample essentially depends on the surface
polarization energy, even in the thermodynamic limit where the body size tends
to infinity. It is found that a modification of the surface energy can lead to
a change of the polarization response by a factor of two. The origin of the
effect is an electric field produced by surface dipoles induced by the strain
gradient. The unexpected sensitivity of the polarization response to the
surface energy in the thermodynamic limit is conditioned by the fact that the
moments of the surface dipoles may scale as the body size
Optical polarization observations with the MASTER robotic net
We present results of optical polarization observations performed with the
MASTER robotic net for three types of objects: gamma-ray bursts, supernovae,
and blazars. For the Swift gamma-ray bursts GRB100906A, GRB110422A, GRB121011A,
polarization observations were obtained during very early stages of optical
emission. For GRB100906A it was the first prompt optical polarization
observation in the world. Photometry in polarizers is presented for Type Ia
Supernova 2012bh during 20 days, starting on March 27, 2012. We find that the
linear polarization of SN 2012bh at the early stage of the envelope expansion
was less than 3%. Polarization measurements for the blazars OC 457, 3C 454.3,
QSO B1215+303, 87GB 165943.2+395846 at single nights are presented. We infer
the degree of the linear polarization and polarization angle. The blazars OC
457 and 3C 454.3 were observed during their periods of activity. The results
show that MASTER is able to measure substantially polarized light; at the same
time it is not suitable for determining weak polarization (less than 5%) of dim
objects (fainter than 16). Polarimetric observations of the optical
emission from gamma-ray bursts and supernovae are necessary to investigate the
nature of these transient objects.Comment: 31 pages, 12 figures, 4 tables; Exposure times in Table 2 have been
correcte
Photometric observations of the supernova 2009nr
We present the results of our UBVRI CCD photometry for the second brightest
supernova of 2009, SN 2009nr, discovered during a sky survey with the
telescopes of the MASTER robotic network. Its light and color curves and
bolometric light curves have been constructed. The light-curve parameters and
the maximum luminosity have been determined. SN 2009nr is shown to be similar
in light-curve shape and maximum luminosity to SN 1991T, which is the prototype
of the class of supernovae Ia with an enhanced luminosity. SN 2009nr exploded
far from the center of the spiral galaxy UGC 8255 and most likely belongs to
its old halo population. We hypothesize that this explosion is a consequence of
the merger of white dwarfs
Single-Dose Bioequivalence Study of Rivaroxaban-Containing Medicinal Products in Healthy Volunteers
Therapeutically, new oral anticoagulants (NOACs) are considered to be non-inferior or superior to vitamin K antagonists (warfarin). NOACs are included in current guidelines for the treatment of various cardiovascular diseases. Rivaroxaban medicinal products have been shown to effectively fight thrombotic complications of the new coronavirus infection, COVID-19. The wide clinical use of rivaroxaban products motivates the development of generics.The aim of the study was to compare the pharmacokinetics and safety of rivaroxaban medicinal products in a single-dose bioequivalence study in healthy volunteers under fasting conditions.Materials and methods: the bioequivalence study compared single-dose oral administration of Rivaroxaban, 10 mg film-coated tablets (NovaMedica Innotech LLC, Russia), and the reference product Xarelto®, 10 mg filmcoated tablets (Bayer AG, Germany), in healthy volunteers under fasting conditions. The open, randomised, crossover trial included 46 healthy volunteers. Each of the medicinal products (the test product and the reference product) was administered once; blood samples were collected during the 48 h after the administration. The washout between the study periods lasted 7 days. Rivaroxaban was quantified in plasma samples of the volunteers by high performance liquid chromatography coupled with tandem mass spectrometry (HPLC-MS/MS).Results: no adverse events or serious adverse events were reported for the test and reference products during the study. The following pharmacokinetic parameters were obtained for Rivaroxaban and Xarelto®, respectively: Cmax of 134.6 ± 58.0 ng/mL and 139.9 ± 49.3 ng/mL, AUC0–48 of 949.7 ± 354.5 ng×h/mL and 967.6 ± 319.9 ng×h/mL, AUC 0–∞ of 986.9 ± 379.7 ng×h/mL and 1003.6 ± 320.4 ng×h/mL, T1/2 of 8.2 ± 3.2 h and 7.8 ± 3.3 h. The 90% confidence intervals for the ratios of Cmax, AUC0–48, and AUC0–∞ geometric means were 88.04–108.67%, 89.42–104.92% and 89.44–104.81%, respectively.Conclusions: the test product Rivaroxaban and the reference product Xarelto® were found to have similar rivaroxaban pharmacokinetics and safety profiles. The study demonstrated bioequivalence of the medicinal products
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