ASSESSMENT OF ANTIOXIDANT ACTIVITY OF WITLOOF CHICORY HERB (CICHORIUM INTYBUS L.)

Problems of regulation of oxidative stress and the search for biologically active substances with antioxidant activity are the focus of researchers. Chicory (Cichorium intybus L.) is a plant containing various biologically active substances (hydroxycinnamic acid, flavonoids, coumarins, ascorbic acid, carotenoids, etc.), exhibiting antioxidant properties. The aim of our study was to evaluate the effect of aqueous and alcoholic extracts of chicory herbs on the processes of free radical oxidation in model systems in vitro using rapid method of determining antioxidant activity, based on the registration of chemiluminescence. A model system generating active oxygen species (ROS) was phosphate buffer with the addition of luminol solution and sodium citrate to initiate reactions involving the formation of ROS injected Fe2+ salt solution. Impact of extracts on lipid peroxidation was studied in chicken yolks homogenized in phosphate buffer. For initiation of oxidation reactions Fe2+ solution was used. Lipid peroxidation (LPO) processes were judged by the light intensity. The effect of aqueous and alcoholic extracts of common chicory herbs in various concentrations on the processes of free radical oxidation in the active forms of oxygen in the system (ROS) and LPO was researched. The study revealed the ability of the extracts of the chicory herb suppress the generation of ROS and LPO in model systems that characterizes their antioxidant properties, which are most pronounced when administered aqueous extracts of chicory herbs compared with alcohol in model systems at a concentration of 0.1 mg/ml

Исследование неустойчивости Тейлора-Гертлера в струях с помощью кинетического подхода

The aim of the paper is to study the unstable processes in free supersonic unstable jet flows. The direct method of solving a kinetic equation is used. For numerical solution the finitedifferent schemes are applied. To perform parallel computations a supercomputer MVS-100K is used. The maximum number of processors was 480. A mechanism of instability for a supercritical regime for 3D flows is investigated. Solutions of these problems are made for flows in a wide range of Knudsen number Kn with different aspect ratio of the orifice (square and rectangular forms). Mach number Ma = 1.4 and a ratio of pressure in the orifice and the background pressure np = 3.16. Comparison with results of known experiments is made. In calculations we have observed that for a subcritical regime with the large Knudsen numbers (small Reynolds numbers) a vorticity of the flow fields in the cross sections is equal zero. For supercritical regimes a system of streamwise pair vortices is obtained. That corresponds to theoretical and experimental data. The paper studies such a system of the Taylor-Görtler vortices in different cross-sections in an initial region of a jet. It presents results of numerous computations. When modeling a roughness in the nozzle orifice it has been found that the character of instability with disturbance of the symmetry in the cross-sections downstream is complicated. Based on direct method to solve the kinetic equation the paper, for the first time, studies in detail the character of 3D instability.Previously, these problems were solved by continuum methods and also for some variants of flows was used the Direct Simulation Monte Carlo method. A potential field of application of the given results is theoretical and experimental investigations with more detailed, in comparison with previous studies, description of unstable supersonic flows, which show the similar features of the Taylor-Görtler instability. Based on conducted study the paper comes to conclusion that the direct methods of the kinetic approach allow us to describe appropriately a mechanism of the transition to the unstable flows in supersonic jets. We believe that a further study will make it possible to show up the characteristics of turbulence in free supersonic jets.С помощью прямого метода решения S-модельного кинетического уравнения Больцмана численно исследуются течения в сверхзвуковых нерасчетных струях. Алгоритм ре-шения основан на явно-неявной схеме и для повышения эффективности распараллелен с помощью MPI (Message Passing Interface). Расчеты выполнены на суперкомпьютере MVS-100K. Изучается влияние геометрии отверстия и степени разреженности газа на механизм возникновения неустойчивости Тейлора-Гёртлера. Показано, что для течений при больших числах Кнудсена (малых числах Рейнольдса) неустойчивость не возникает. При переходе к закритическим режимам (малые числа Кнудсена) в поле течения возникает система продольных вихрей, соответствующая неустойчивости Тейлора-Гёртлера, что согласуется с теоретическим и опытным данными. Кроме того, при наличии дополнительного возмущающего фактора - шероховатости по периметру отверстия, обнаружена потеря поперечной симметрии струи вниз по потоку. DOI: 10.7463/mathm.0116.083362

EBSD characterization of cryogenically rolled type 321 austenitic stainless steel

Electron backscatter diffraction was applied to investigate microstructure evolution during cryogenic rolling of type 321 metastable austenitic stainless steel. As expected, rolling promoted deformation-induced martensitic transformation which developed preferentially in deformation bands. Because a large fraction of the imposed strain was accommodated by deformation banding, grain refinement in the parent austenite phase was minimal. The martensitic transformation was found to follow a general orientation relationship, {111}γ||{0001}ε||{110}α′ and 〈110〉γ||〈11-20〉ε||〈111〉α′, and was characterized by noticeable variant selection

Kinetic Approach-based Investigation of TaylorGörtler Instability in Jets

The aim of the paper is to study the unstable processes in free supersonic unstable jet flows. The direct method of solving a kinetic equation is used. For numerical solution the finitedifferent schemes are applied. To perform parallel computations a supercomputer MVS-100K is used. The maximum number of processors was 480. A mechanism of instability for a supercritical regime for 3D flows is investigated. Solutions of these problems are made for flows in a wide range of Knudsen number Kn with different aspect ratio of the orifice (square and rectangular forms). Mach number Ma = 1.4 and a ratio of pressure in the orifice and the background pressure np = 3.16. Comparison with results of known experiments is made. In calculations we have observed that for a subcritical regime with the large Knudsen numbers (small Reynolds numbers) a vorticity of the flow fields in the cross sections is equal zero. For supercritical regimes a system of streamwise pair vortices is obtained. That corresponds to theoretical and experimental data. The paper studies such a system of the Taylor-Görtler vortices in different cross-sections in an initial region of a jet. It presents results of numerous computations. When modeling a roughness in the nozzle orifice it has been found that the character of instability with disturbance of the symmetry in the cross-sections downstream is complicated. Based on direct method to solve the kinetic equation the paper, for the first time, studies in detail the character of 3D instability.Previously, these problems were solved by continuum methods and also for some variants of flows was used the Direct Simulation Monte Carlo method. A potential field of application of the given results is theoretical and experimental investigations with more detailed, in comparison with previous studies, description of unstable supersonic flows, which show the similar features of the Taylor-Görtler instability. Based on conducted study the paper comes to conclusion that the direct methods of the kinetic approach allow us to describe appropriately a mechanism of the transition to the unstable flows in supersonic jets. We believe that a further study will make it possible to show up the characteristics of turbulence in free supersonic jets