Results are provided for a study of refractory objects based on fuzed periclase after service in the suction pipe of an RH-degasser in two metallurgical enterprises. In one enterprise the pipe operates in contact with slag, containing fluorspar with an alumina slag-forming component as a homogenizing addition, and in the second with slag for whose homogenization only fluorspar is used. In both cases, but in different pipe service conditions, there are 100 melts, and the operating duration is 1550 – 1800 min. It is established that the depth of molten slag component filtration into refractory depends on the form slag homogenizing additive in the steel-pouring ladle. Slag containing a combination of feldspar with alumina slag-forming additive penetrates into the refractory microstructure to a greater depth, which leads to a change in the initial phase composition of an object with formation of a considerable amount of secondary phases.

FactSageTM software is used successfully in the Gruppa Magnezit engineering section making it possible to calculate thermodynamic equilibria in multicomponent systems, to construct phase diagrams, and to calculate viscosity in molten slags and glasses, etc. Use of specialized software makes it possible to both analyze premature wear of linings, and also the preliminary selection of refractory compositions, slag modifiers or directly for slag regimes optimum from the point of view of fulfilling metallurgical tasks and reducing refractory specific consumption. Modeling results are provided for processes occurring within ferrous and nonferrous metallurgy units.

The results of studies of refractory products based on the fused periclasechromite after service in the suction pipe of the RH vacuum at two metallurgical plants were reported. At one plant, the branch pipe was operated in contact with slag containing as a homogenizing additive fluorspar with an alumina slag-forming component, on the second with slag, for homogenization, which was used only by fluorspar. The duration of operation is 1550‒1800 min. It is established that the depth of infiltration of the slag melt components into the refractory depends on the type of homogenizing additive to the slag in the steel casting ladle. A slag containing a combination of fluorspar with an aluminous slag-forming additive penetrates the microstructure of the refractory to a greater depth, which leads to a change in the initial phase composition.

Aprocedure is presented for studying flake graphite used in OOO Gruppa Magnezit for quality evaluation and possible application in carbon-containing material manufacture. Results are provided for studying graphite from various deposits within Russia, China, Brazil, India, Norway, and Africa. The significance of entirely new graphite quality indices and their interpretation is demonstrated in accordance with the procedure proposed.

The experimental test procedure is presented for the flaky graphites quality estimation and for the possibility of their application in the carbon-containing materials production as it is employed at the «Magnesit Group» Ltd. The research results are given for the graphites of various deposits of Russia, China, Brazil, India, Norway, Africa. The importance of the new graphite's quality parameters proposed in connection with the developed procedure and their interpretation are shown in the article. Ill. 16. Ref. 6. Tab. 8.

A new digital analysis procedure is developed for microstructural study of fuzed periclase structural elements aimed at objectivity. The main parameters are presented distinguishing the proposed method from a normal linear method by means of chords. An example is provided of crystal sizes for fuzed periclase produced by the Magnezit Group and other producers, measured by old and new methods. Checking fuzed periclase with an MgO content of more than 97.5% with a different CaO/SiO2 ratio in periclase-carbon refractories did not reveal the effect of this parameter on life in a steel-pouring ladle lining.

A new method of estimating the fused periclase quality – the revision of international standards. Quality and service life of refractories on the basis of fused periclase depend to a large extent upon the size of periclase crystals and its mineralogical composition. During fusion of periclase it is impossible to obtain completely homogeneous material with identical crystals size. That is why it is generally accepted to evaluate quality of fused periclase by the average crystals size. Measurements of this item are usually done with the help of generally adopted method of chords, which was developed in the last century and has a number of drawbacks. Magnezit Group developed a new objective method of digital analysis during microscopic examination of structural elements of fused periclase. It allows to considerably improve objectivity of obtained data. The main feature of the new method is application of the system of images analysis, which allows to carry out in automatic mode measurements on the preliminary created digital model of the whole area of the polished section. With the help of the digital model it is possible to calculate average size of fused periclase crystals taking into account number of crystals as well as percentage of the area occupied by them. Does CaO/SiO2 ratio influence service life of refractories? New view of old rules. Till today it was considered that one of the characteristics of fused periclase quality is coefficient of basicity – CaO/SiO2, ratio, which should be more than 2. Magnezit Group carried out investigations of coarse-crystalline fused periclase with MgO >97.5 % content and with various CaO/SiO2 ratios. We present in this report the main study results: if the impurities content is low in the fused periclase with MgO >97.5 %, then coefficient of basicity exerts limited influence onto the service life of periclase-carbon bricks.

The "Magnezit" Group has developed a new method and equipment for testing the resistance of refractory products to slag and clinker on rotary kilns. The method makes it possible to objectively evaluate the effectiveness of a given refractory as a lining material for equipment operating at high temperatures.

Summarized material is presented, characterizing the pore space of refractories, whose analysis makes it possible to make recommendations for controlling production parameters in order to prepare refractories with a desired pore structure. The results obtained are based on known research of the pore space, different pore classifications, and also the authors’ industrial and experimental experience.

OOO Gruppa Magnezit has developed a new generation of periclase cement-free concretes based on a MgO–SiO2 binder with a service temperature from 1500 to 1700°C depending on filler composition. The technology assimilated makes it possible to prepare refractories of complex shape for lining elements of CBCM intermediate ladles and other units.

A system of microscopic and physicochemical analysis methods is used to study a number of periclase-chromite composition objects. Microstructural changes of refractories during service in heating units for nickel preparation are studied from the results obtained.

The cardioprotective, inotropic, and antiarrhythmic effects of U-50.488, a selective agonist of κ1 opioid receptors (κ1 ORs), was studied using the model of 45-min total ischemia and 30-min reperfusion of isolated rat heart. Cardiac κ1 ORs were stimulated by adding U-50.488 to the perfusing solution up to the final concentration of 0.1 or 1 μmol/l. The opioid had no influence on the incidence of reperfusion arrhythmias. The addition of 0.1 μmol/l U-50.488 reduced the reperfusion release of creatine phosphokinase (CPK) by half, which positively correlated with the decrease in the myocardial cAMP content (r = 0.89, p < 0.01). At the same time, the addition of U-50.488 in the higher concentration (1 μmol/l) had no effect on either cAMP level or CPK release. These results indicate that the cardioprotective effect of U-50.488 may be connected with the reduction of myocardial cAMP content. Activation of κ1 ORs caused a decrease in both frequency and amplitude of myocardial contractions. The negative inotropic and chronotropic effect of U-50.488 was shown to be independent of changes in the myocardial cAMP content. A hypothesis is proposed that the absence of any cardioprotective effect of U-50.488 at the higher concentration (1 μmol/l) is accounted for by its interaction with unknown nonopioid receptors of cardiac myocytes.

We studied the effect of allotransplantation of bone marrow mononuclear cells on postinfarction remodeling of the heart in rats. The cells were transplanted into the periinfarction zone of the heart. The transplantation was performed on day 9 after coronary occlusion. It was found that on day 45 after coronary occlusion myocardial hypertrophy developed, ventricular fibrillation threshold decreased, but myocardial contractility remained within the normal. Allotransplantation of bone marrow mononuclear cells had no effect on myocardial hypertrophy and did not prevent the development of electrical instability of the heart.

With the aim of selecting possibilities for use in industry of chromite ores from different deposits in order to produce periclase-chromite refractories these ores are studied by optical and electron microscopy, and also chemical and differential thermal analysis: Indian, Iranian, South African and Turkish. High temperature changes that occur within them are described. Microstructural features for periclase-chromite refractories based on these chromite ores and the interconnection of indices are revealed that make it possible to recommend an ore for a specific application.

The cardioprotective and antiarrhythmic effects of a selective κ1-opioid receptor agonist U-50,488 were studied during experimental 45-min total ischemia and 30-min reperfusion of isolated rat heart. The opioid had no effect on the incidence and type of reperfusion arrhythmias. U-50,488 in a concentration of 0.1 µM inhibited reperfusion-induced release of creatine phosphokinase and decreased cAMP concentration in the myocardium by 2 times. These parameters remained unchanged after treatment with U-50,488 in a concentration of 1 µM. The cardioprotective effect of U-50,488 was probably associated with a decrease in cAMP concentration in heart cells. U-50,488 in a concentration of 1 µM produced no cardioprotective effect, which can be explained by its interaction with an unknown non-opioid receptor in cardiomyocytes.

Results are presented for a physicomechanical study of a refractory torcrete-mix grade PMT-86 produced by OOO Gruppa Magnezit. The wear intensity of a mix during operation in intermediate ladles is evaluated. Service properties are analyzed for torcrete-mix grade PMT-86 compared with imported analogs, and the high competitiveness of the mix and its attractive price and quality are demonstrated.

Intravenous infusion of D-Ala 2 ,Leu 5 ,Arg 6 -enkephalin (dalargin) caused bradycardia in narcotized rats. This effect was not observed during opioid receptor blockade with naloxone, naloxone methiodide, and norbinaltorphimine. Dalargin and (-)-U-50,488 added to Krebs—Henseleit perfusion solution for isolated rat heart decreased heart rate. Ganglionic blocker hexamethonium potentiated the negative chronotropic effect of dalargin. The negative chronotropic effect of dalargin is probably associated with activation of cardiac κ-opioid receptors. It should be noted that dalargin caused tachycardia in some animals. This reaction was not observed after treatment with hexamethonium. The positive chronotropic effect of dalargin is probably related to modulation of the parasympathetic autonomic nervous system. Agonists and antagonists of δ-opioid receptors caused persistent bradycardia. We hypothesized that selective δ-opioid antagonists exhibit properties of partial δ-receptor agonists.

Activation of cardiac δ-opioid receptors (ORs) by their selective agonist DPDPE (154 nM) increased the resistance of perfused rat heart to ischemia/reperfusion injury. Decreased release of creatine phosphokinase to the perfusate and decreased incidence of arrhythmias were observed during reoxygenation. At the same time, opioidergic decrease in left ventricular developed pressure took place both during the preischemic period and after restoring the coronary circulation. All these effects could be prevented by blocking δ-ORs by naltrindole or inhibition of Ca2+-ATPase of sarcoplasmic reticulum by cyclopiazonic acid. δ-OR agonist DPDPE had no effect on cAMP levels in myocardial tissue during the whole experiment. The obtained data suggest that the antiarrhythmic and cytoprotective effects observed after δ-OR stimulation can be realized through the changes in Ca2+ transport at the level of the sarcoplasmic reticulum