Mass Gap, Abelian Dominance and Vortex Dynamics in SU(2) Spin Model

We discuss a new approach to the investigation of the nature of the mass gap in spin systems with continuous global symmetries which is much analogous to the method of abelian projection in the gauge theories. We suggest that the abelian degrees of freedom, in particular, abelian vortices are responsible for the mass gap generation phenomena in the non-abelian spin systems. To check our hypothesis we study numerically the three-dimensional SU(2) spin model in the Maximal Abelian projection. We find that the abelian mass gap in the projected theory coincides with the full non-abelian mass gap within numerical errors. The study of the percolation properties of the abelian vortex trajectories shows that the phase transition and the mass gap generation in the 3D SU(2) spin model are driven by the abelian vortex condensation.Comment: 12 pages, LaTeX, 4 figures, uses epsf.sty; Fig.3 is replaced and a few comments are adde

X-ray tomography characterization of density gradient aerogel in laser targets

The low-density solid laser target characterization studies begun with the SkyScan 1074 computer microtomograph (CMT) [1, 2] are now continued with higher resolution of SkyScan 1174. The research is particularly focused on the possibility to obtain, control and measure precisely the gradient density polymers for laser target production. Repeatability of the samples and possibility to obtain stable gradients are analysed. The measurements were performed on the mm-scale divinyl benzene (DVB) rods.Publisher PDFPeer reviewe

Synthesis and study of complexes of the novel Russian antiviral drug Camphecene with pentacyclic triterpenes of licorice

For the first time, the complexation of pentacyclic triterpenes of licorice (glycyrrhizic acid (GA) and its aglycone, glycyrrhetinic acid (GLA)) with the novel Russian antiviral drug Camphecene (Camph) was investigated. The complexes obtained at different molar ratios were studied using both UV/Vis spectroscopy and mass spectrometry (ESI MS). Formation of the host:guest complexes were registered: GA and GLA molecular complexes (Camph+2GA; Camph+2GLA) with stability constants К = 6.94 106 М-2 and К = 2.89 106 М-2, respectively. The research results demonstrate a considerable potential of ESI MS as a technique for simple and fast detection of formation of the complexes of GA /GLA and the novel drugs

Invariant measure in hot gauge theories

We investigate properties of the invariant measure for the $A_0$ gauge field in finite temperature gauge theories both on the lattice and in the continuum theory. We have found the cancellation of the naive measure in both cases. The result is quite general and holds at any finite temperature. We demonstrate, however, that there is no cancellation at any temperature for the invariant measure contribution understood as Z(N) symmetrical distribution of gauge field configurations. The spontaneous breakdown of Z(N) global symmetry is entirely due to the potential energy term of the gluonic interaction in the effective potential. The effects of this measure on the effective action, mechanism of confinement and $A_0$ condensation are discussed.Comment: Latex file, 65.5kB, no figure

THE INCREASING THE DURATION OF FUNCTIONAL BEVERAGES METHODS

In the Russia beverage market, functional beverages are increasingly popular with the population due to their intensive lifestyle and worsening environmental situation. Of great importance is the shelf life of drinks, since they determine the presence in the composition of useful nutrients that affect the various systems of functioning of the human body. The main groups of functional compounds are given. Ways to increase the shelf life of beverages, all aspects and their impact on the safety of the functional components of beverages are considered. The role of flavonoids as one of the groups of functional compounds has been evaluated. Recent studies on the effect of certain functional compounds on each other are given.In the Russia beverage market, functional beverages are increasingly popular with the population due to their intensive lifestyle and worsening environmental situation. Of great importance is the shelf life of drinks, since they determine the presence in the composition of useful nutrients that affect the various systems of functioning of the human body. The main groups of functional compounds are given. Ways to increase the shelf life of beverages, all aspects and their impact on the safety of the functional components of beverages are considered. The role of flavonoids as one of the groups of functional compounds has been evaluated. Recent studies on the effect of certain functional compounds on each other are given

Interaction-induced singular Fermi surface in a high-temperature oxypnictide superconductor

In the family of iron-based superconductors, LaFeAsO-type materials possess the simplest electronic structure due to their pronounced two-dimensionality. And yet they host superconductivity with the highest transition temperature Tc=55K. Early theoretical predictions of their electronic structure revealed multiple large circular portions of the Fermi surface with a very good geometrical overlap (nesting), believed to enhance the pairing interaction and thus superconductivity. The prevalence of such large circular features in the Fermi surface has since been associated with many other iron-based compounds and has grown to be generally accepted in the field. In this work we show that a prototypical compound of the 1111-type, SmFe0.92Co0.08AsO, is at odds with this description and possesses a distinctly different Fermi surface, which consists of two singular constructs formed by the edges of several bands, pulled to the Fermi level from the depths of the theoretically predicted band structure by strong electronic interactions. Such singularities dramatically affect the low-energy electronic properties of the material, including superconductivity. We further argue that occurrence of these singularities correlates with the maximum superconducting transition temperature attainable in each material class over the entire family of iron-based superconductors.Comment: Open access article available online at http://www.nature.com/srep/2015/150521/srep10392/full/srep10392.htm

High-temperature superconductivity from fine-tuning of Fermi-surface singularities in iron oxypnictides

In the family of the iron-based superconductors, the $RE$FeAsO-type compounds (with $RE$ being a rare-earth metal) exhibit the highest bulk superconducting transition temperatures ($T_{\mathrm{c}}$) up to $55\ \textrm{K}$ and thus hold the key to the elusive pairing mechanism. Recently, it has been demonstrated that the intrinsic electronic structure of SmFe$_{0.92}$Co$_{0.08}$AsO ($T_{\mathrm{c}}=18\ \textrm{K}$) is highly nontrivial and consists of multiple band-edge singularities in close proximity to the Fermi level. However, it remains unclear whether these singularities are generic to the $RE$FeAsO-type materials and if so, whether their exact topology is responsible for the aforementioned record $T_{\mathrm{c}}$. In this work, we use angle-resolved photoemission spectroscopy (ARPES) to investigate the inherent electronic structure of the NdFeAsO$_{0.6}$F$_{0.4}$ compound with a twice higher $T_{\mathrm{c}}=38\ \textrm{K}$. We find a similarly singular Fermi surface and further demonstrate that the dramatic enhancement of superconductivity in this compound correlates closely with the fine-tuning of one of the band-edge singularities to within a fraction of the superconducting energy gap $\Delta$ below the Fermi level. Our results provide compelling evidence that the band-structure singularities near the Fermi level in the iron-based superconductors must be explicitly accounted for in any attempt to understand the mechanism of superconducting pairing in these materials.Comment: Open access article available online at http://www.nature.com/articles/srep1827

Evaluation of Different Extraction Techniques for the Assay of Anti - Acetylcholinesterase Activity of Olive leaves (Olea europaea)

Received: 19.05.2021. Revised: 21.09.2021. Accepted: 08.11.2021. Available online: 09.11.2021.The total phenol content and the anti-acetylcholinesterase activity were compared in olive leaf (OL) extracts obtained using both subcritical water extraction (SbWE) and conventional solvent extraction (ethanol-water). The method proposed by Ellman (in vitro) was used to study the inhibitory activity of acetylcholinesterase (AChE). The total content of phenolic compounds and AChE activities of OL extracts varied depending on the used extraction method. Thus, the extract obtained using the subcritical water technique (220 °C) showed the highest amounts of total phenolic components, expressed as gallic acid equivalents, (70.4 mg/g raw material) and the highest inhibitory AChE-activity (IC50 = 0.35 mg/ml). The obtained values of the anti-AChE activity of the extracts of OL demonstrated that the inhibitory activity for SbW-extract 120 °C (IC50 = 2.92 mg/ml) and SbWextract 180 °C (IC50 = 0.8 mg/ml) is higher than that of the traditional extract (IC50 = 3.6 mg/ml), respectively. These results indicate a great potential of the subcritical water technique to develop the techniques to produce commercial extracts of OL, and these results could encourage improved utilization of the OL. The collected data on the anti - acetylcholinesterase activity of olive leaves clearly demonstrate the prospects for use of OL extracts in the development of novel pharmaceutical substances and nutraceuticals for the prevention and/or the treatment of Alzheimer's disease as well as some other neurodegenerative diseases.This work was supported by the Ministry of Science and Higher Education of the Russian Federation (State assignment in the field of scientific activity, project No 0852-2020-0031) and the Russian Foundation for Basic Research (RFBR, grant no. 19-33-90211-Aspiranty (S. S. Khizrieva))