264 research outputs found
Analytical description of stationary ideal MHD flows with constant total pressure
Incompressible stationary flows of ideal plasma are observed. By introduction
of curvilinear system of coordinates in which streamlines and magnetic force
lines form a family of coordinate surfaces, MHD equations are partially
integrated and brought to a certain convenient form. It is demonstrated that
the admissible group of Bogoyavlenskij's symmetry transformations performs as a
scaling transformation for the curvilinear coordinates. Analytic description of
stationary flows with constant total pressure is given. It is shown, that
contact magnetic surfaces of such flows are translational surfaces, i.e. are
swept out by translating one curve rigidly along another curve. Explicit
examples of solutions with constant total pressure possessing a significant
functional arbitrariness are given
Products of chemical reactions that occur during high-temperature heat treatment of the meat products
Recently the actively active studies have begun devoted to the accumulation of «harmful» substances in food products, which are supposedly accumulated in the body of a person who often consumes these products. Meat, as a source of full-featured animal protein, is especially popular in this aspect. For the preparation of meat products various types of heat treatment are used, almost each of which will inevitably lead to the destruction of some of the chemical compounds originally present in the product, and the formation of completely new chemical compounds, which can often be harmful to the human body. During high-temperature heat treatment (mainly frying), some chemical reactions in meat products occur, which lead to the formation of heterocyclic aromatic amines (HAA) in it. Due to the great variety of raw meat and cooking recipes, during the heat treatment HAA’s of various classes are formed, each of them will be peculiar for the particular type of raw material or recipe components (with the exception of MeIQx and PhIP, which always form during frying). The more complete understanding of the HAA’s formation mechanism will help study the products of Maillard reactions and Strecker degradation. In this work we studied the formation of HAA’s as a result of the cyclization of creatine and the detaching of water (dehydration) from it during temperature exposure. The classification of the compounds formed as a result of these reactions is presented and the main classes of the HAA obtained in result are considered. The questions of the influence of various factors on amount of HAA formed, such as the fat content, the introduction of Fe2+, Fe3+, are raised. In the future it is necessary to conduct studies of the quantitative content of HAA in meat products to complement the already actively ongoing work on the study of xenobiotics consumed by humans with food, which will give a more comprehensive picture of the carcinogens content in food products
Core of the Magnetic Obstacle
Rich recirculation patterns have been recently discovered in the electrically
conducting flow subject to a local external magnetic termed "the magnetic
obstacle" [Phys. Rev. Lett. 98 (2007), 144504]. This paper continues the study
of magnetic obstacles and sheds new light on the core of the magnetic obstacle
that develops between magnetic poles when the intensity of the external field
is very large. A series of both 3D and 2D numerical simulations have been
carried out, through which it is shown that the core of the magnetic obstacle
is streamlined both by the upstream flow and by the induced cross stream
electric currents, like a foreign insulated insertion placed inside the
ordinary hydrodynamic flow. The closed streamlines of the mass flow resemble
contour lines of electric potential, while closed streamlines of the electric
current resemble contour lines of pressure. New recirculation patterns not
reported before are found in the series of 2D simulations. These are composed
of many (even number) vortices aligned along the spanwise line crossing the
magnetic gap. The intensities of these vortices are shown to vanish toward to
the center of the magnetic gap, confirming the general conclusion of 3D
simulations that the core of the magnetic obstacle is frozen. The implications
of these findings for the case of turbulent flow are discussed briefly.Comment: 14 pages, 9 figures, submitted to Journal of Turbulenc
Pharmacological correction of immune disorders in patients with chronic heart failure and ischemic heart disease
Currently, there are few data on the effect of cardiovascular drugs on the immune status of patients with heart failure (HF). This paper provides information on the impact of ß-adrenergic blocking agent (BAB), angiotensin-converting enzyme inhibitors (ACEI) on the maintenance of markers of immune inflammation in the blood, as well as on inhibition of synthesis of tumor necrosis factor-α (TNF-α) and on blocking of interaction between TNF-α and membrane receptor
Clinical efficacy of a betablockers therapy in patients with chronic heart failure on the background of postinfarction cardiosclerosis
Despite the fact that betablockers (BBs) are one of the main groups of therapy of patients with acute myocardial infarction (AMI), the comparative effectiveness of various BBs in patients with postinfarction cardiosclerosis (PICS) is uncertain. There was performed comparative analysis of clinical efficacy of BBs in patients with chronic heart failure (CHF) on the background of coronary heart disease (CHD), PICS. There was evaluated the impact of metoprolol succinate, carvedilol, bisoprolol and betaxolol on blood pressure (BP), left ventricular ejection fraction (LVEF), change the functional class of chronic heart failure, and mortality in patients over 4 year
Absolute and convective instabilities in an inviscid compressible mixing layer
We consider the stability of a compressible shear flow separating two streams
of different speeds and temperatures. The velocity and temperature profiles in
this mixing layer are hyperbolic tangents.
The normal mode analysis of the flow stability reduces to an eigenvalue
problem for the pressure perturbation. We briefly describe the numerical method
that we used to solve this problem. Then, we introduce the notions of the
absolute and convective instabilities and examine the effects of Mach number,
and the velocity and temperature ratios of each stream on the transition
between convective and absolute instabilities. Finally, we discuss the
implication of the results presented in this paper for the heliopause
stability.Comment: 5 pages, 6 figures, accepted by Astronomical Notes (Astron.
Nachrichten
Flux and field line conservation in 3--D nonideal MHD flows: Remarks about criteria for 3--D reconnection without magnetic neutral points
We make some remarks on reconnection in plasmas and want to present some
calculations related to the problem of finding velocity fields which conserve
magnetic flux or at least magnetic field lines. Hereby we start from views and
definitions of ideal and non-ideal flows on one hand, and of reconnective and
non-reconnective plasma dynamics on the other hand. Our considerations give
additional insights into the discussion on violations of the frozen--in field
concept which started recently with the papers by Baranov & Fahr (2003a;
2003b). We find a correlation between the nonidealness which is given by a
generalized form of the Ohm's law and a general transporting velocity, which is
field line conserving.Comment: 9 pages, 2 figures, submitted to Solar Physic
Splitting technique for analytical modelling of two-phase multicomponent flow in porous media
In this paper we discuss one-dimensional models for two-phase Enhanced Oil Recovery (EOR) floods (oil displacement by gases, polymers, carbonized water, hot water, etc.). The main result presented here is the splitting of the EOR mathematical model into thermodynamical and hydrodynamical parts. The introduction of a potential associated with one of the conservation laws and its use as a new independent coordinate reduces the number of equations by one. The (n) × (n) conservation law model for two-phase n-component EOR flows in new coordinates is transformed into a reduced (n − 1) × (n − 1) auxiliary system containing just thermodynamical variables (equilibrium fractions of components, sorption isotherms) and one lifting equation containing just hydrodynamical parameters (phase relative permeabilities and viscosities). The algorithm to solve analytically the problem includes solution of the reduced auxiliary problem, solution of one lifting hyperbolic equation and inversion of the coordinate transformation. The splitting allows proving the independence of phase transitions occurring during displacement of phase relative permeabilities and viscosities. For example, the minimum miscibility pressure (MMP) and transitional tie lines are independent of relative permeabilities and phases viscosities. Relative motion of polymer, surfactant and fresh water slugs depends on sorption isotherms only. Therefore, MMP for gasflood or minimum fresh water slug size providing isolation of polymer/surfactant from incompatible formation water for chemical flooding can be calculated from the reduced auxiliary system. Reduction of the number of equations allows the generation of new analytical models for EOR. The analytical model for displacement of oil by a polymer slug with water drive is presented.Adolfo P. Pires, Pavel G. Bedrikovetsky, Alexander A. Shapir
Study of sedative tea phytocomplex within the framework of studies aimed at creation of a rectal dosage form with antihistaminic effect
We designed a new complex drug with antiallergic effect containing, in addition to the main component loratadine, a phytocomplex for an extra therapeutic effect. A collection of plants with sedative activity is chosen and the optimal agent for extraction of bioactive compound
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