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Studying of single-molecule magnets has sprung many surprises such as, e.g., quantum tunneling of the magnetization, which is strongly related to the presence of a magnetic anisotropy. Electron spin resonance and inelastic neutron scattering measurements of (PPh4)2[ReF6]⋅2H2O complex evidence an unprecedented large single-site magnetic anisotropy of $$D \sim 35$$ K in this material. Using state-of-the-art ab initio calculations we found that the single-ion anisotropy is indeed very large (but does not exceed 12 K) and revealed the physical mechanism lying behind this phenomenon.

The paper presents the study results of diabases of rare-earth and beryllium-containing deposit of the Republicof Belarusin order to determine their suitability for the production of silicate materials and products for various purposes. The data obtained allowed developing raw compositions and optimizing the technological parameters to produce glass, mineral fibers, glass ceramics, stone casting, ceramic bricks and tiles, as well as porous aggregates. The regularities of structure and phase formation during high-temperature treatment of raw compositions of silicate materials using diabases are established. The results of the work allow us to establish the features of the production of silicate materials containing diabase as main raw material of compositions, to increase mineral and raw-materials base of Belarusand to improve the environmental situation in mining enterprises.

The results of full study of X-ray photoelectron spectra (XPS) of spin-liquid candidate CuAl2O4 including the measurements of high-energy resolved core level (Cu 2p, Al 3p, O 1s), Cu LMM Auger and valence band spectra are presented. The comparison of obtained results with spectra of reference samples and specially performed density functional theory calculations has confirmed a finite Cu site-disorder in CuAl2O4, where about 30% of Cu2+ ions occupy the octahedral sites. Obtained valence band spectra can be used in further theoretical studies aimed on the investigation of electronic and magnetic properties of this mysterious ma-terial. © 2021, The Author(s). The DFT calculations were supported by the Russian Science Foundation (project no. 20-62-46047). The XPS measurements were supported by the Ministry of Science and Higher Education of the Russian Federation (theme Electron no. AAAA-A18-118020190098-5 and project FEUZ 2020-0060). I.S. Zhidkov acknowledges the support of the Council of the President of the Russian Federation for State Support of Young Scientists and Leading Scientific Schools (project no. MK-989.2020.2).

The results of full study of X-ray photoelectron spectra (XPS) of spin-liquid candidate CuAl2O4 including the measurements of high-energy resolved core level (Cu 2p, Al 3p, O 1s), Cu LMM Auger and valence band (VB) spectra are presented. The comparison of obtained results with spectra of reference samples and specially performed density functional theory calculations has confirmed a finite Cu site-disorder in CuAl2O4, where about 30% of Cu2+ ions occupy the octahedral sites. Obtained valence band spectra can be used in further theoretical studies aimed on the investigation of electronic and magnetic properties of this mysterious material.

Data on the mechanism of plasminogen activation by streptokinase, tissue and urokinase-type plasminogen activators (PAs) is reviewed. The regulatory role of fibrin in plasminogen activation involving its direct interaction with tissue-type PA and indirect interaction with streptokinase and urokinase-type PAs is demonstrated. Information on the current PAs use in thrombolytic therapy is also presented. The complications arising with administration of such thrombolytic agents are analyzed and the causes of complications are supposed. Recent information on the development of new PAs is also reviewed. The results of studies of PA mutant derivatives synthesized by recombinant DNA techniques as well as chimeric (hybrid) forms of PAs and their chemically synthesized conjugates are presented. The trend in search for PAs is analyzed. A new direction in the study of PAs for combined plasminogen activation and further development of the methods of thrombolytic therapy is outlined.

The mechanism of plasminogen activation by streptokinase, tissue and urokinase-type plasminogen activators (PAs) were reviewed. The regulatory role of fibrin in plasminogen activation involving its direct interaction with tissue-type PA and indirect interaction with streptokinase and urokinase-type PAs was demonstrated. Recent information on the development of new PAs is also displayed. The result of studies of PA mutant derivatives synthesized by recombinant DNA techniques are discussed. Date on chimeric (hybrid) forms of PAs and their chemically synthesized conjugates are presented. The trend in search for PAs is analysed. A new direction in the study of PAs for combined plasminogen activation and the further development of the methods of thrombolytic therapy was outlined.

The mechanism of protein C system functioning and role of its components in the regulation of the coagulation and the fibrinolysis was considered in the review. There are also new data about the anticoagulation, profibrinolysis and antiinflammatory functions of protein C system. Activated protein C is inhibited by the protein C inhibitor, alpha 1-antitripsin, and inhibitor of tissue activator plasminogen-1. Hereditary or acquired deficiency of protein C, protein S and thrombomodulin lead to thrombotic diseases. Injection of exogenous recombinant protein C or activated protein C into the blood increases the anticoagulant activity of the blood and produced the antithrombotic effect.

Factor IX is a factor of the blood coagulation system. Its activation occurs on the surface of phospholipid membranes. It can be activated by the factor VIIa-TF (tissue factor)-Ca2+ complex via an extrinsic pathway and by factor XIa in the presence of Ca2+ via the intrinsic pathway of blood coagulation system activation. The activated factor IXa is a serine proteinase. The main function of the activated factor IXa in complex with factor VIIIa and phospholipids in presence of Ca2+ consists of the activation of factor X. Factor IX is synthesized in the liver and is subject to a number of posttranslational modifications including gamma-carboxylation, beta-hydroxylation, and glycosylation. It forms a subgroup of vitamin K-dependent plasma proteins including factors VII and X and protein C characterized by identical domain structures having high levels of homology. Factor IX consists of an NH2-terminal Gla domain, two epidermal growth factor (EGF)-like domains, and a C-terminal domain containing Ser in its active site. Factor IX deficiency in human plasma results in the disease known as hemophilia B.

Modification of the method for factor IX activity determination was proposed. A mixture of chicken plasma and human plasma was used as factor IX-deficient substrate plasma. Moreover determinations were performed in the lack of kaolin-activator of factor XII. This allowed simplifying the assay performance. The described modification may be used to determine factor IX activity in its concentrates with the aim of diagnosis of haemophilia B and control of the disease treatment.

The existing methods for determination of activity of the VII, VIII, IX and X factors of the coagulation system have been analyzed. The comparative evaluation of their efficiency which depends on complexity, reprocibility, sensibility and test performance time is considered. The important role of these methods in scientific investigation for the diagnosis of haemophilia A, haemophilia D, factors VII and X deficiency for the purposes of therapy is emphasized.

The kinetic investigation was carried out on the inhibition of hydrolysis of N, alpha-benzoyl-D, L-arginine-p-nitroanilide (BApNA) for bovine and salmon trypsin by phenylmethanesulphonyl fluoride (PMSF), N, alpha-tosyl-L-lysine chloromethyl ketone (N-TLCK), N, alpha-tosyl-L-phenylalanine chloromethyl ketone (N-TPCK). Kinetic parameters of inhibition (Ki, k2) by PMSF for salmon and bovine trypsin differ insignificantly. The k2/Ki value of N-TPCK for salmon trypsin is 10 times more than of bovine trypsin. Kinetic parameters of inhibition by N-TLCK had the less difference. The Ki value of this inhibitor for salmon trypsin is 5 times less than that of bovine trypsin and k2 value is 1.7 times less.

The complement system represents a multitude of activating factors, associated with the cellular membrane and providing for cell lysis. The system is composed of 21 serum proteins and 8 receptors and may be found in cells of various types. The major function of the system consists in its activation which entails a cascade of events terminated by cell lysis. Two complement system activation mechanisms are generally distinguished, one of which is classical and one is alternative. These two mechanisms converge after the activation of the third component (C3) or as a result of interaction between the terminal components (C5, C6, C7, C8 and C9) of the complement cascade. The complement system is linked with the fibrinolytic, blood coagulating and kinin systems.

A comparative kinetic analysis of Pacific salmon and bovine trypsins revealed that the former hydrolyzes p-nitroanilide-N,L-benzoyl-D,L-arginine (BApNA) with a far greater efficiency in comparison with bovine trypsin due to the decrease in Km. The inhibition constants for the BApNA hydrolysis by bovine and salmon trypsin with glycine, beta-alanine, L-lysine, L-arginine and benzamidine were determined. With an increase in the length of the hydrocarbon chain in the inhibitor molecule (i.e., in the order of glycine-beta-alanine-L-lysine) the inhibiting effect increased both with salmon and bovine trypsins. The Ki values for benzamidine and L-arginine appeared to be by one order of magnitude higher with salmon trypsin than with bovine trypsin. L-arginine was a much more effective inhibitor compared to L-lysine when both salmon and bovine trypsins were used.

Upon electrochemical reduction in aprotic media, N,N-disubstituted hydrazones of benzaldehyde and benzoyl chloride undergo aminonitrile splitting.

1. The reduction of 2-oxy-4,6-dimethylpyrimidine in aqueous buffer solutions and on electrodes with low hydrogen-overvoltage (Pt and Rh) proceeds through an electrocatalytic mechanism leading to the formation of 2-oxo-4,6-dimethyl-1,3-diazacyclohexane. 2. The fact that neither the solution pH nor the nature of the metal had any effect on the reduction rate could be due to peculiarities in the adsorptional behavior of the 2-oxy-4,6-dimethylpyrimidine.

1. A study was made of the hydrogenation rate of chaleone in aqueous dioxane solution at electrodes with a variable hydrogen overvoltage. 2. At a Pt/Pt electrode the process proceeds by an electrocatalytic mechanism with the formation of dihydrochalcone. The dimeric product is formed at Hg and poisoned Pt electrodes.

Conditions are developed for determining potential activity of plasminogen in amine groups formed in casein hydrolysis. Two variants of determination are suggested: by means of a ninhydrin reagent and trinitrobenzene sulphoacid. The method permits determining 0.02-0.1 of plasmin casein units (cas. units); it is 20 times as sensitive as the known caseinolytic method based on determination of the degree of tyrosine absorption.

Kringles K1-3, K4 and K5 are studied for their effect on tissue plasminogen activator-induced fibrin clot lysis in the presence of Glu- and Lys-plasminogen. It is established that kringles K4 and K5 inhibit fibrinolysis of Glu-plasminogen, and K1-3--that of Lys-plasminogen. The role of plasminogen molecule kringles in the plasminogen interaction with fibrin polymer is discussed.

It was shown that activation of two native plasminogen and miniplasminogen forms by the tissue activator in the presence of fibrin obeys the Michaelis-Menten kinetics. The kinetic parameters of activation of both plasminogen native forms differ insignificantly. For miniplasminogen whose molecule contains no lysine-binding sites, a marked decrease of activation power was observed. The Km value of activator for miniplasminogen is 10 times that of plasminogen form I and 20 times that of plasminogen form II. The kcat/Km value of activator for miniplasminogen is 7 times less than that of plasminogen form I and by one order of magnitude more than that of plasminogen form II. These results testify to the importance of lysine-binding sites in the native plasminogen molecule during the activation of fibrinolysis by the major physiological activator.