Analysis of optical magnetoelectric effect in GaFeO_3

We study the optical absorption spectra in a polar ferrimagnet GaFeO_3. We consider the E1, E2 and M1 processes on Fe atoms. It is shown that the magnetoelectric effect on the absorption spectra arises from the E1-M1 interference process through the hybridization between the 4p and 3d states in the noncentrosymmetry environment of Fe atoms. We perform a microscopic calculation of the spectra on a cluster model of FeO_6 consisting of an octahedron of O atoms and an Fe atom displaced from the center with reasonable values for Coulomb interaction and hybridization. We obtain the magnetoelectric spectra, which depend on the direction of magnetization, as a function of photon energy in the optical region 1.0-2.5 eV, in agreement with the experiment.Comment: 18 pages, 5 figure

Optimization of methods of quality control drug steroid structure for example glucocorticosteroid

This paper presents an original method for the analysis of corticosteroids with the use of reversed-phase high performance liquid chromatography. A mixture of 1% aqueous formic acid and ethyl alcohol at a ratio of 10 to 90 was taken as an eluting system for corticosteroids. This ratio of solvents in the mobile phase ensures control of the rate of movement of corticosteroids in the column. Since corticosteroids are freely soluble in alcohol, using 90% of this solvent in the mobile phase ensured optimum retention time of these compound

Phytochemical, microbiological, and technological studies in the field of obtaining a hydroalcoholic extract with antimicrobial activity from the liquorice root

Phytochemical composition and antimicrobial activity of hydroalcoholic extracts from the liquorice root with the use of different concentrations of ethanol have been studied. The optimal range of ethanol concentration of 65±15% v/v has been found. The dependency between the integral index of antimicrobial activity of the extract and concentration of glycyram and licuroside has been foun

Independent ferroelectric contributions and rare-earth-induced polarization reversal in multiferroic TbMn2O5

Three independent contributions to the magnetically induced spontaneous polarization of multiferroic TbMn2O5 are uniquely separated by optical second harmonic generation and an analysis in terms of Landau theory. Two of them are related to the magnetic Mn3+/4+ order and are independent of applied fields of up to 7 T. The third contribution is related to the long-range antiferromagnetic Tb3+ order. It shows a drastic decrease upon the application of a magnetic field and mediates the change of sign of the spontaneous electric polarization in TbMn2O5. The close relationship between the rare-earth long-range order and the non-linear optical properties points to isotropic Tb-Tb exchange and oxygen spin polarization as mechanism for this rare-earth induced ferroelectricity.Comment: 8 pages, 5 figure

Laser-driven quantum magnonics and THz dynamics of the order parameter in antiferromagnets

The impulsive generation of two-magnon modes in antiferromagnets by femtosecond optical pulses, so-called femto-nanomagnons, leads to coherent longitudinal oscillations of the antiferromagnetic order parameter that cannot be described by a thermodynamic Landau-Lifshitz approach. We argue that this dynamics is triggered as a result of a laser-induced modification of the exchange interaction. In order to describe the oscillations we have formulated a quantum mechanical description in terms of magnon pair operators and coherent states. Such an approach allowed us to} derive an effective macroscopic equation of motion for the temporal evolution of the antiferromagnetic order parameter. An implication of the latter is that the photo-induced spin dynamics represents a macroscopic entanglement of pairs of magnons with femtosecond period and nanometer wavelength. By performing magneto-optical pump-probe experiments with 10 femtosecond resolution in the cubic KNiF$_3$ and the uniaxial K$_2$NiF$_4$ collinear Heisenberg antiferromagnets, we observed coherent oscillations at the frequency of 22 THz and 16 THz, respectively. The detected frequencies as a function of the temperature ideally fit the two-magnon excitation up to the N\'eel point. The experimental signals are described as dynamics of magnetic linear dichroism due to longitudinal oscillations of the antiferromagnetic vector.Comment: 25 pages, 10 figure

Simplified mathematical modeling of the distribution process of licuroside and glycyram between the extractant and Glycyrrhizae radices

Theoretical development of the extraction process is an important task for further modeling and calculation of optimal conditions for extraction of biologically active compounds from the plant raw material. The aim of the study was to propose and test a theoretical model to describe the process of Licuroside and Glycyram distribution between the solid phase of Glycyrrhiza radices and the extractant. For studies, we used Glycyrrhiza radices (Liquorice roots). For extraction, we used plant raw material with particle size of 0.1-0.5 mm, and ethanol-water solution 70 % v/v was used as an extractan

Polyphenolic Compounds Composition Study in Ocimum basilicum L. Herb and the Development of Their Quantification Assessment

The article demonstrates the study results of the garden basil chemical composition - Ocimum basilicum L. It is established that the basic polyphenols of a plant are hydroxycinnamic acids - rosemary, caftaric, chlorogenic. Flavonoids, the dominant of which is routine, are presented in smaller quantities. An optimal method for the quantitative determination of O. basilicum L. polyphenols is offere