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Speech disorders are quite common in preschool age and provoke violations not only of verbal, but also of personal and social relationships. In children with speech disorders, depending on the duration of the visit to the speech kindergarten, the function of speech, praxis, gnosis, memory, attention, and thinking were studied using test tasks. It is established that children who attend speech kindergarten for the first year, as well as children who stay in this institution for the second year, have some features in the state of praxis and mnestic functions. Against the background of correctional measures, the majority of children aged 6-7 years (by the third year of attending a speech kindergarten) have a state of higher brain functions that practically does not differ from their peers from a mass kindergarten.

A method has been proposed for calculating linear dynamic magnetization of a viscoelastic ferrocolloid in a constant magnetic field (displacement field). The magnetic phase of the colloid consists of Brownian ferromagnetic nanoparticles placed into a Jeffry’s fluid. Therefore, each particle, upon its rotation induced by an alternating (probe) field, dissipates energy via two friction “channels” operating in parallel. The usual (Newtonian) viscosity prevails at short times, while the retarded (Maxwellian) dissipative interaction plays the main role at long times. It has been shown that the retarded friction on the Jeffry’s medium gives rise to a slow magnetization relaxation mode, which must be most pronounced in ferrocolloids having substantial elasticity. As the displacement field is enhanced, this mode weakens and the friction relevant to the Newtonian viscosity becomes prevailing, because it causes small-angle orientational fluctuations of particle magnetic moments. The proposed method yields an exact solution of the model, and the results obtained using method prove that previous approximate calculations are substantially limited.

A model is developed to describe the oscillations of optical anisotropy induced in a viscoelastic ferrocolloid (nanodispersion of magnetic particles) by an AC magnetic field. The viscoelasticity of the matrix (carrier medium) is assumed to obey the Jeffreys rheological scheme, whose advantage is that with the aid of just two viscous parameters and a single one for elasticity it enables one to vary the retarded mechanical response of the carrier from a weakly Maxwellian fluid to a medium with the rheology of a Kelvin gel. As the orientational motion of the particles driven by the AC field is always strongly affected by thermal motion, the occurring process is described with the aid of a kinetic (Fokker–Planck type) equation that combines diffusional and drift terms. On this basis, an exact evolution equation for the macroscopic optical anisotropy of a ferrocolloid is derived that is, however, just one link in an infinite chain of equations for statistical moments. The solution is obtained by applying effective field approximation: reducing the number of moment equations to their minimum and closing the chosen set. This solution is substituted to the scheme of a standard polarimetric set-up, and it is demonstrated how the peculiarities imparted by viscoelasticity should manifest themselves on the intensity of the light transmitted through the set up containing a ferrocolloid sample. This article is part of the theme issue ‘Transport phenomena in complex systems (part 2)’.

A model has been proposed for the complete (2D) orientational Brownian motion of axially symmetric particles in a Kelvin viscoelastic medium. It has been shown that the elastic response of the carrier medium can be correctly determined by introducing an additional variable, the moment elastic forces, which, together with the particle-orientation vector, composes the complete set of phase variables of a system. A set of stochastic equations (Langevin equations) has been derived for these values. This set has been employed to construct, under the effective field approximation, a simple set of moment equations describing the magnetization dynamics of a ferrogel, i.e., a dispersion of single-domain nanoparticles in a gel matrix. The theoretical results qualitatively agree with the data of magnetic microrheology of gelatin-based ferrogels.

The theory of orientational motion of a Brownian magnetic nanoparticle embedded in a viscoelastic medium and subjected to a time-dependent uniform magnetic field is developed. The rheology of the viscoelastic environment of the particle is modeled by the Jeffreys scheme, which under variation of a minimal number of parameters is able to resemble a wide range of soft materials: from a weakly structured (nearly Newtonian) polymer solution to a gel. It is shown that in the Jeffreys model, the diffusional orientational motion of a particle is a combination of two modes, which could be associated with a fast motion within the polymer mesh cell and a slow displacement that involves deformation of the mesh, respectively. The dependencies of the reference times of both relaxation modes on the Jeffreys viscous and elastic parameters and temperature are found. It turns out that in substantially viscoelastic media, the rate of the slow mode (it dominates in relaxation) quadratically depends on the matrix temperature. This effect does not have analogs in linearly viscous systems. For an ensemble of magnetic nanoparticles in viscoelastic and gel Jeffreys matrices: (1) the dynamic magnetic susceptibility is derived and evaluated both within an exact approach and in a simple approximation; (2) the problem of magnetic relaxometry, i.e., evolution of magnetization after step-wise turning off the field, is solved; (3) the specific power loss caused by viscous dissipation generated by the particles under an ac field is analyzed as a function of the rheological parameters. Results (1) and (2) provide simple models for magnetic nanorheology; consideration (3) advances the physics of magnetic hyperthermia in viscoelastic and gel-like media.

The effect of field-induced plasticity (magnetic shape memory) displayed by polymer composites filled with multi-domain ferromagnetic microparticles is discussed. Such a soft magnetic elastomer (SME) magnetizes, that is, the filler particles acquire magnetic moments only upon application of an external magnetic field. ‘Switching-on’ of interparticle magnetic interactions essentially affects the internal structure of SMEs since the magnetic forces by far exceed the high-elasticity ones due to attachment of the particles to the polymer matrix. According to the hypothesis, in a SME there self-organizes a network of clusters that gives birth to the effect of internal dry friction and by that imparts plasticity to the composite. Field-induced structuring, together with plasticity, disappears as soon as the external field is turned off. Under these conditions, elastic forces no longer experience any resistance and move the particles back to their initial spatial positions: the sample ‘recalls’ its initial shape. To account for the above-described plasto-elastic behavior of a magnetized SME, a structure-mechanical model (scheme) is proposed, which comprises the elastic elements (springs) and the entities (Saint-Venant elements) mimicking the dry-friction effect. The elements of the model are heuristically identified with two networks. One of them is related to the polymer matrix as itself, while another resembles the particle clusters formed due to the field-induced magnetic interactions. Both networks are interwoven and may deform only affinely. On the basis of the model, the tensile deformation cycles obtained in experiments on the two types of SMEs made of weakly-linked silicone rubber filled with carbonyl iron microparticles are interpreted. The tested SMEs differ by the dispersity of the filler. The samples of the first type contain only ‘fine’ iron particles with the size of 2-5 microns, while in the SME of the second type the filler consists of equal (by weight) amounts of ‘fine’ and ‘coarse’ (~70 microns) particles. The cycles measured under a number of external fields are presented. By fitting experimental data, the parameters of the theoretical scheme are evaluated, and their dependence on the applied field strength is determined. For the field dependencies of the scheme parameters of the isotropic SMEs examined here, the expressions borrowed from the phenomenology of textured SMEs are taken and tested, proving their applicability for this case.

Orientational Brownian motion of a solid nanoparticle embedded in a viscoelastic medium modelled by the Jeffreys fluid is studied. The particle bears a magnetic moment and is subjected to a combination of a constant (bias) and a weak (probing) AC magnetic fields. First, the set of Langevin equations of the problem is presented and then on that basis a corresponding kinetic equation (KE) is derived. The solution of the KE that is linear with respect to the AC field amplitude is worked out. This solution is virtually exact since it is cast as a series that enables one to obtain the result with arbitrary accuracy. In that framework, a closed expression for the dynamic magnetic susceptibility of a statistical ensemble of magnetic particles in a viscoelastic environment is found, analyzed and compared to the previously existed approximate solution. It is shown that: (i) the dynamic elasticity of the medium has a substantial effect on the magnetic spectra; (ii) to correctly describe this effect, one has to retain a considerable number of terms in the series that presents the KE solution.

The Monte Carlo method, which is a powerful tool for finding equilibrium states (and/or their corresponding characteristics) in systems of a different nature in many cases allows one to also describe the course of kinetic processes. This work presents the Monte Carlo modeling of magnetic relaxation and dynamics of induced magnetization of an ensemble of ferromagnetic nanoparticles. It is shown by comparison with the exact solution that in both problems there is a proportionality between the number of calculation steps and the physical duration of the transition or periodic process. On this basis, relationships are proposed making it possible to estimate the time interval corresponding to a single Monte Carlo step. For the process of magnetic relaxation the obtained result is a generalization of the well-known Nowak-Chantrell-Kennedy formula for the case of particles with finite magnetic anisotropy.

With allowance for orientational Brownian motion, the magnetorelaxometry (MRX) signal, i.e., the decay of magnetization generated by an ensemble of ferromagnet nanoparticles, each of which bears a macromolecular corona (a loose layer of polymer gel) is studied. The rheology of corona is modelled by the Jeffreys scheme. The latter, although comprising only three phenomenological parameters, enables one to describe a wide spectrum of viscoelastic media: from linearly viscous liquids to weakly-fluent gels. The “transverse” configuration of MRX is considered where the system is subjected to a DC (constant bias) field, whereas the probing field is applied perpendicularly to the bias one. The analysis shows that the rate of magnetization decay strongly depends on the state of corona and slows down with enhancement of the corona elasticity. In addition, for the case of “transverse” MRX, we consider the integral time, i.e., the characteristic that is applicable to relaxation processes with an arbitrary number of decay modes. Expressions for the dependence of the integral time on the corona elasticity parameter and temperature are derived.

A simple rheological model is introduced to describe the plasticity in soft magnetic elastomers induced by an external field. In addition to the elasticity of the polymer matrix, the effect of dry friction (plasticity), which is provided by the rearrangement of the spatial structure of a dispersed magnetic subsystem in the course of the deformation of the material by a sufficiently strong field, is taken into account in the model. Model parameters are estimated from the reported experimental data on the deformation of cylindrical samples based on a soft silicon elastomer filled with quasispherical microparticles of carbonyl iron.

Monte Carlo method with a variable number of calculation steps is used for simulations of the magnetization dynamics in a microsphere consisting of a non-magnetic core coated with a layer of magnetic nanograins. Namely, the dynamic magnetic hysteresis under an AC field in such a core-shell microsphere is considered for the cases of non-interacting particles and with allowance for the interparticle dipole-dipole interaction. The time portions corresponding to one calculation step are estimated from comparison of the Monte Carlo-Metropolis results and a numerically-exact solution of the kinetic equation.

The ground magnetic state of systems of finite number N of single-domain particles confined in a spherical monolayer is investigated by numeric simulations. Two model situations are considered. In the first, the particle positions are imposed and fixed, in the second, the particles are able to move freely within the layer; in the latter case the excluded volume effect is taken into account. It is found that in all the range studied ( N ⩽200) the ground state of the system retains a considerable extent of magnetic vorticity (toroid moment). Moreover, the magnetic and toroid moments are correlated: they are approximately perpendicular to one another.

Results are provided for introducing an injection system for supply of lube feedstock and solvent during selective treatment with furfurol. A marked increase in the efficiency of extraction and the subsequent production stage for basic oils, i.e. deparaffinizing of raffinates, is demonstrated.

The influence of a magnetic field on the viscosity of dilute dispersion of spherical magnetohard particles in viscoelastic matrix, the Maxwell liquid with a single relaxation time, is studied. Calculations are performed on the basis of the equation of rotational diffusion derived previously by the authors. It is shown that the effective viscosity of magnetic fluid decreases in the presence of a field. This unexpected result is clearly explained in physical terms.

Theory of Brownian motion of a fine particle in a viscoelastic fluid continuum is developed. The rheology of the embedding medium is described in terms of classical structure (spring-and-damper) schemes. It is shown that a great variety of conceivable ramifications of such structures could be reduced to an effective Jeffreys model: a Maxwell chain shunted by a damper. This scheme comprises just three material parameters: two for viscosities (fast and slow) and one for elasticity. For the thermal motion of a particle in such a fluid, the set of Langevin equations is derived. In the cases of 1D translational and 2D orientational (rotation about fixed axis) motions, the time dependencies of mean-square displacements are found analytically. It is shown that in a Jeffreys fluid, the Brownian motion has three regimes: fast diffusion (short times), slow diffusion (long times) and a crossover of those resulting in virtual localization (dynamic confinement) of the particle. Experimental evidence for that taken from the literature is presented. The developed formalism is applied to the particles with “frozen-in” dipole moments, whose orientational motion is a combination of Brownian diffusion and regular excitation by an AC field. The dynamic susceptibilities are calculated for the ensembles of particles liable for either 2D or 3D rotations. Comparison shows that the out-of-phase part of the susceptibility χ ′′(ω ) in 3D case differs considerably from that of 2D case. Function χ (ω ) for the forced 3D rotary diffusion in a Jeffreys fluid is found for the first time. In our view, it would be useful for realistic theoretical interpretation of microrheology data and the more so for estimating the particle-mediated AC field-induced heating (magnetic hyperthermia) in viscoelastic fluid media.

The in vitro model of isovolumic beating heart revealed enhanced sensitivity of the hearts from rats survived severe brain injury to concentration of Ca(2+), Na(+), and H(+) ions in the perfusion solution. Inhibition of myocardial contractile function after trauma was accompanied by destruction signs in cardiomyocyte sarcolemma and mitochondrial dysfunction.

A ferroparticle driven by an AC field in a Maxwell fluid is studied with regard to magnetic microrheology. Orientational kinetics is simplified by neglecting the particle rotary inertia. While in a Newtonian fluid the inertialess approximation for nanoparticles is valid practically unboundedly, in a viscoelastic matrix there exists an important restriction on the stress relaxation time. Assuming weak non-equilibrium, the magneto-orientational relaxation times and low-frequency magnetic spectra are found in the presence of a constant (bias) field. Another way of particle-mediated probing of the matrix involves the field-induced birefringence of a suspension; under zero bias field the corresponding (quadratic) susceptibility is found.

Groups comprising few rigid magnetic dipoles (single-domain particles) organized in a regular flat N -polygon pattern are considered. The group is subjected to a constant magnetic field in the plane of the structure and responds to the field by magnetization in the same plane. In such a cluster, along with the magnetization, another order parameter does exist: the toroid moment. External field induces magnetization and suppresses the toroid moment. If the matrix of the cluster complies elastically to the interparticle forces, two types of behavior are possible. The particles may either slightly approach one another or undergo a collapse which results in their tight clotting.

A kinetic description is given for the suspension of dipole particles in the viscoelastic matrix simulated by the Maxwell liquid with one relaxation time. The possibility of the brief description of the orientational kinetics of the particles is considered with their inertia being disregarded. It is shown that the case of the Maxwell matrix is fundamentally different than the case of a Newtonian liquid, where the inertialess approximation for the particles with sizes of ∼10 nm has a practically unlimited domain of applicability. For viscoelastic suspension, the inertialess approximation denotes a rather strict constraint on the time of stress relaxation τ M . Times of orientational relaxation of the magnetization of a viscoelastic system and spectra of its low-frequency dynamic susceptibility in the presence of a constant biasing field are found in the approximation of the effective field (the slightly nonequilibrium state).

Description of the magneto-orientational dynamics of single-domain ferroparticles embedded in a viscoelastic fluid or in a weak gel is constructed on the basis of the Langevin equation that takes into account the non-Newtonian properties of the matrix and the Brownian motion of the particle. For the mentioned complex media, dynamic magnetic susceptibilities are obtained and shown to possess some interesting quasi-resonance properties.

The dynamics of magnetization is theoretically studied for a system of ferromagnetic nanoparticles suspended in a gel (a ferrogel). The Brownian motion impedes orientation of the particles determined by the elastic matrix. Therefore, the main parameter of the medium determining the static magnetic susceptibility value is the ratio of the modulus of elasticity of matrix to the temperature. The dispersion factors of dynamic susceptibility components include combinations of the velocities of several processes: elastic restoration of the orientation of particles, their rotational Brownian diffusion, and viscous relaxation of the inertial motion. The absorption of the energy of the alternating field in a ferrogel is found to be lower than in an isotropic magnetic suspension. The effect of the interaction of elastic and Brownian forces on the effective times of ferrogel magnetization relaxation is monitored.

Nonlinear dynamic magneto-orientational susceptibility responsible for the induced birefringence in a viscoelastic magnetic suspension is investigated. In the model, the particles are considered to be magnetically rigid and their mechanical inertia is taken into account. The rheology of the fluid matrix is of the Maxwell type. We show that the frequency spectra of the field-induced birefringence presents a number of specific lineshapes.

A numerical model is proposed for simulating the magnetic properties of a system (N-cluster) comprising a finite number N of monodomain particles uniformly distributed over a spherical surface. The calculation algorithm is based on the Monte Carlo method. In the absence of an external magnetic field, the magnetic moment of any spherical N-cluster vanishes due to the formation of vortex structures, with a measure of vorticity offered by the toroid moment Q. The results of model calculations show that the value of Q in N-clusters with 4 < N < 20 amounts to about 80% of the maximum and is virtually independent of N, while exhibiting weak even-odd oscillations.

A Fokker-Planck equation (FPE) for an assembly of Brownian particles suspended in a viscoelastic fluid is studied. The particles are assumed to possess rigid dipole moments due to which their orientation is affected by an external field. The equilibrium solution of FPE in the presence of the field is constructed. With allowance for the particle inertia, the dynamic elasticity (i.e., the retarded stress) of the carrier fluid, yields a non-trivial contribution to the distribution function.

We present a model to describe a dynamic orientational response of a dilute suspension of single-domain magnetic particles in a viscoelastic liquid carrier of the Maxwell fluid type. Introducing Brownian orientational diffusion into the equation of the particle rotary motion, absorption spectra of the initial dynamic magnetic susceptibility are obtained. Under appropriate conditions they display a complex comblike structure which might be helpful for probing the local rheology of the carrier medium of a suspension. \textcopyright{} 1996 The American Physical Society.

Monte Carlo modeling of superparamagnetic kinetics is addressed with regard to quantification of the simulation steps in units of real time. For the classical N\'eel case (field-free relaxation of the magnetic moment in a single-domain uniaxial particle), a modification of the Nowak-Chantrell-Kennedy formula is proposed enabling the calculations with the variation amplitude of the magnetic moment independent of the particle anisotropy. This relation is obtained from comparison of the Monte Carlo simulated relaxation against the solution of the kinetic equation for the particle magnetic moment. The same idea is applied to a strongly nonequilibrium process: steady re-magnetization of a superparamagnetic particle under an ac field. It is found that in the latter case a linear relationship can be established between the number of simulation steps and the real-time scale (the field period) that holds fairly well in wide frequency and anisotropy parameter intervals.

The orientational dynamics of Brownian single-domain ferroparticles suspended in a viscoelastic (Maxwellian) fluid have been studied. For a two-dimensional model, i.e., disk-like particles rotating in their plane, the Langevin equation is derived and solved approximately to yield the dynamic susceptibility. The conditions under which a resonance caused by the dynamic elasticity of the fluid matrix of the suspension would appear, are discussed.

A statistical molecular model of polymer networks, which takes into account inter-molecular orientational interaction and constancy of the chain contour length, is proposed. A simple formula for the network free energy valid for any deformations is obtained. A system of equations which describes orientational-elastic interactions in polymer networks is derived. The influence of deformation and degree of cross linking on the conditions of network phase transition into the orientationally ordered state of the nematic type is studied. The deformation curves considerably deviate from those predicted by the classical elasticity theory. A comparison of the proposed theory with experimental data for natural rubbers is carried out.

It was demonstrated in experiments on male rats that acute lethal blood loss and subsequent resuscitation after 4- and 6-min clinical death induce lipid peroxidation processes, decreased antioxidant enzyme activity, cause activation of anaerobic glycolysis in the myocardium. This metabolic heart impairment causes hemodynamic instability in postresuscitation period. 25 mg/kg of carnosine injected during resuscitation decreased functional-metabolic heart impairments and hemodynamic disarrangement as well as early postresuscitation lethality. The authors attribute positive carnosine effect to its significant antioxidant activity.

The steady three-dimensional flow of a perfect gas over blunt bodies is investigated using a model of a hypersonic viscous shock layer. Analytical formulas are obtained for the distribution of the heat flux on the side surface with respect to its value at the stagnation point using the integral method of successive approximations. It is shown that at moderate and high Reynolds numbers the distribution of the relative heat flux depends slightly on the Reynolds number and on other gas-dynamic parameters of the flow. The accuracy of the formulas obtained is estimated by comparing them with the results of numerical solutions of the three-dimensional viscous shock layer equations for bodies of various shape. Similar formulas are obtained in [1]for the neighbourhood of a plane of symmetry of three-dimensional bodies. Note that, unlike the formulas for the relative heat fluxes assumed in boundary-layer theory (for example, [2, 3]), the formulas proposed here do not require values of the flow parameters on the outer edge of the boundary layer (i.e. the calculation of three-dimensional inviscid flow) and a calculation of the inviscid streamlines on the surface. They depend only on the geometrical characteristics of the body.

A method of solving three-dimensional flow problems with the aid of two-dimensional solutions, which can be used for any Reynolds numbers, is proposed. The method is based on the use of similarity relations obtained in the theoretical analysis of the approximate analytic solution of the equations of a three-dimensional viscous shock layer. These relations express the heat flux and the friction stress on the lateral surface of a three-dimensional body in terms of the values on the surface of an axisymmetric body. The accuracy is estimated by comparing the results with those of a numerical finite-difference calculation of the flow past bodies of various shapes. Similar similarity relations were previously obtained in [1] for the plane of symmetry of a blunt body.

Three-dimensional chemically-nonequilibrium flow past blunt bodies in the neighborhood of the plane of symmetry is investigated within the framework of viscous shock layer theory. The similarity of three-dimensional and axisymmetric flows, previously established in [1] for a uniform gas, is extended to chemically-nonequilibrium gas flows. It is shown that the problem of determining the heat fluxes and friction stress in the neighborhood of the line of flow divergence can be reduced to the problem of determining these quantities for the axisymmetric body. The validity of the axisymmetric analogy is verified by carrying out numerical calculations for bodies of different shapes re-entering the earth's atmosphere along a gliding trajectory. Various models of surface catalytic activity are considered. The use of similarity relations makes it possible to apply existing programs for calculating axisymmetric flows to the solution of three-dimensional problems.

Cardiac contractile function in the acute period after brain injury (BI) was studied on 158 non-inbred male albino rats, by using the isolated isovolumetrically contracted heart according to the procedure described by Fallen et al. The injured rats showed a significantly depressed left ventricular myocardial contractility during the hypoxic test, followed by reoxygenation, a lower positive chronic inotropic effect, and an increased diastolic defect with an enhanced rate of cardiac stimulation rates. Brain injury increased the dependence of cardiac performance on the concentration of Ca2+ in the perfused solution. The findings suggest the decreased resistance of the hearts of the rats that had sustained BI to pathogenetic factors.

We study magnetic response of an assembly of ferroparticles suspended in a viscoelastic matrix which is modeled by a Maxwell fluid with a unique stress relaxation time. The problem refers to the magnetic microrheology approach where deformational properties of a complex fluid are tested with the aid of embedded nanoparticle probes set to motion by an external ac magnetic field. A possibility is considered to simplify the description of the orientational kinetics of the system at the expense of neglecting inertia effects in particle rotary motion. It is shown that in this aspect a Maxwell matrix differs essentially from the Newtonian one. In the latter the inertialess approximation for the particles of the approximately 10nm size is valid practically unboundedly. For a viscoelastic matrix the inertialess approximation means an important restriction on the value of the stress relaxation time. Assuming weak nonequilibrium, the magneto-orientational relaxation times are found and low-frequency magnetic spectra of a viscoelastic suspension are determined in the presence of a constant (magnetizing) field.

Theoretical model to describe magnetodynamics of a ferrogel, i.e., an assembly of ferromagnetic nanoparticles embedded in a gel, is proposed. The reorientations of the particles are determined by the influence of the elastic matrix and the rotational Brownian motion. The set of essential parameters, on which the components of the dynamic magnetic susceptibility tensor depend, is discussed. In the framework of the model, absorption of the energy of an ac field is studied. With allowance for the interaction of elastic and Brownian forces, the effective relaxation times and eigenfrequencies for the longitudinal and transverse components of the ferrogel magnetization are evaluated.

Theoretical model to describe magnetodynamics of a ferrogel, i.e., an assembly of ferromagnetic nanoparticles embedded in a gel, is proposed. The reorientations of the particles are determined by the influence of the elastic matrix and the rotational Brownian motion. Due to the interplay between these two factors, the main parameter characterizing the static magnetic susceptibility of the system is the ratio of the elastic modulus of the matrix times particle volume to the thermal energy. It is shown that the main components of the dynamic magnetic-susceptibility tensor are determined by the combinations of the reference rates of several processes inherent to the system, namely, the elastic restoration of the particle orientation, Brownian rotary diffusion, and viscous relaxation of the particle angular momentum. In the framework of the model, absorption of the energy of an alternating external field by a ferrogel is studied. With allowance for the ever present interaction of elastic and Brownian forces, the effective relaxation times for the longitudinal and transverse components of the ferrogel magnetization are evaluated.

The model of 4-min clinical death due to acute blood loss was used to study cardiac contractility, myocardial metabolism and causes of endotoxemia in early postresuscitation period. The investigations were made on the whole body, isolated, isovolemically contracting heart and isolated papillary muscle. A marked reduction in functional myocardial reserves, maximal within the first 24 hours of postresuscitation, with dominant defects in relaxation was seen. Pathogenetic factors responsible for cardiodepression are the following: hypoxia, impairment of bioenergetics, hyperactivation of lipid peroxidation, acidosis, membrane destruction, endotoxemia.

An approximate similarity relationship is obtained that permits determination of the heat flux in the neighborhood of the plane of symmetry during three dimensional chemically nonequilibrium flow around bodies to be reduced to the heat flux computation at the stagnation point of an axisymmetric body.

Activation of serum enzymes in male rats was detected during the postresuscitation period after 4-6-min clinical death as a result of membrane destruction. Increase in the rate of lipid peroxidation and impairments of energy metabolism in the myocardium were responsible for destruction of cardiomyocyte biomembranes. Administration of carnosine (25 mg/kg body weight) simultaneously with compensation for blood loss obviated the membrane lipid bilayer destruction and contributed to the development of the optimal conditions for membrane-bound enzymes.

The frequency and nature of heart rhythm disturbances have been studied in experiments on random-bred male rats who survived 4- and 6-min clinical deaths of acute blood loss. Using correlation analysis it has been shown that the leading pathogenetic arrhythmogenic factors are: catecholamine excess, as well as excess of free fatty acids, lipid peroxidation products, lactate and Ca-ATPase inhibition. The efficacy of preventive (gutimin, inderal, oxipiridin-6, isoptin) and therapeutic (carnozin, creatinphosphate) use of the drugs affecting pathogenetic mechanisms of heart arrhythmias and thus stabilizing bioelectrical heart activity in the early postresuscitation period has been observed.

It was demonstrated in experiments on male rats that acute lethal blood loss and subsequent resuscitation after 4- and 6-min clinical death induce lipid peroxidation processes, decreased antioxidant enzyme activity, cause activation of anaerobic glycolysis in the myocardium. This metabolic heart impairment causes hemodynamic instability in postresuscitation period. 25 mg/kg of carnosine injected during resuscitation decreased functional-metabolic heart impairments and hemodynamic disarrangement as well as early postresuscitation lethality. The authors attribute positive carnosine effect to its significant antioxidant activity.