Search

The paper presents results of experimental studies aimed at introducing laser ignition of fuel mixtures into aero-space design practice. The source of ignition energy was a semiconductor laser featuring fibre radiation output, operating in a quasi-continuous wave mode. We carried out experiments for oxygen--hydrogen and oxygen--methane fuel types. The purpose of our research was to demonstrate the fundamental possibility of implementing fuel ignition by means of this type of laser, using a rocket engine igniter and a low-thrust rocket engine as examples. Employing semiconductor lasers directly as an ignition source for fuel mixtures in aerospace technology is attractive as it may feasibly reduce the requirements for thermal conditions during operation of the laser ignition system on board a rocket or spacecraft, as well as expand the range of permissible vibration and shock loads. The paper presents experimental results that delineate operating parameter ranges and operation cyclograms for the devices under consideration that ensured stable ignition of oxygen--hydrogen and oxygen--methane fuel mixtures; we also list the required power parameters for a semiconductor laser. The investigation revealed the specifics of using a semiconductor laser-based ignition system, which will be useful in developing laser rocket launching devices, ensuring reliable repeated on-off functionality

This paper is about a comparative analysis of the requirements of the Russian standard, the standard of the European Union and the PRC for overhead contact wires for electrified high-speed railways. New generation contact wires must have a high level of mechanical, electrical and operational properties. The Russian standard does not regulate the chemical composition of alloys used for the contact wires manufacture. Unlike the standards of the European Union and China, the Russian standard regulates the maximum value of the relative creep. Compositions, mechanical properties, electrical resistivity and recrystallization temperature for the contact wires with a cross section of 120 mm2 are given. The requirements for the material for the contact wire are presented. The need to use more durable conductive materials instead of copper is noted since mechanical loads and operating temperatures are constantly increasing. The values of mechanical properties, recrystallization temperature and creep of contact wires made of copper alloys are given. Based on the analysis results of the literature data and the experiments, alloys of the Cu-Mg system are recommended as a material for the contact wire manufacture for an overhead network system for high-speed railways.

Arbutin is the main active ingredient in many herbal medicinal products that have diuretic, antimicrobial, bactericidal, and antioxidant effects. Many of these products are mixtures of different herbal substances. Therefore, the approaches to quality control of HMPs can vary significantly. The aim of the study was to compare arbutin assay procedures used in quality control of arbutin-containing products. Materials and methods. Samples of the following HMPs were used in the study: monocomponent Bearberry Leaf and multicomponent Brusniver® (herbal mixture, powder). The test methods used were titrimetry, ultraviolet-visible spectrophotometry, and high-performance liquid chromatography (HPLC). Results. The authors compared five arbutin assay procedures described in the monographs and product files for arbutin-containing HMPs. Conclusions. It has been established that the analysed procedures cannot be used interchangeably as equivalent test methods; the limits for arbutin have to be established for each specific procedure. Iodometric titration is the most labour- and time-consuming method, and the determined titration endpoint is a subjective assessment. Spectrophotometric methods do not require the use of an arbutin reference standard, but they can give overestimated results as compared to the HPLC and titrimetry methods. HPLC methods are more selective, but they require the use of reference standards. The recommended test methods for HMP quality control are HPLC and visible spectrophotometry; the titrimetric method is recommended for replacement.

The NiFe/Cu/IrMn heterostructures with a variable number of interlayer Cu atoms exhibit a sharp change in the exchange-bias field, the coercive force, and the unidirectional anisotropy field at an effective copper layer thickness tCu ≈ 0.5 nm, which corresponds to incomplete coverage of the interface, i.e., to an island deposited structure. The symmetry of the angular dependence of the ferromagnetic resonance changes sharply at an incompletely coated interface (tCu = 0.5 nm), which corresponds to a transition from isolated islands to a magnetic fractal structure. This phenomenon, which can be called a “magnetic” percolation threshold is not related to the electrical resistance of the heterostructure, which decreases sharply at a significantly larger effective threshold copper layer thickness (tCu = 1.3 nm) when the interface is completely covered.

Stable crystalline complexes of Co(II) acetylacetonate [Co(II)(acac)2], trifluoacetylacetonate [Co(II)(tfac)2] and hexafluoroacetylacetonate [Co(II)(hfac)2] with triphenodioxazines (TPDOs) were synthesized and their structures studied using X-ray crystallography. In the crystal, complexes [Co(II)(tfac)2]TPDO and [Co(II)(hfac)2]TPDO form infinite ⋯N⋯Co⋯N⋯ chains featuring 1D coordination polymeric structures, whereas in the [Co(II)(acac)2]TPDO complex, the Co(acac)2 units fill only half of the possible crystallographic positions. The electron accepting trifluoro substituents in the diketonate moieties significantly enhance the thermal stability of the complexes with TPDO. Of all the complexes, only [Co(II)(hfac)2]TPDO does not dissociate into the components in solution. In all studied complexes, the Co(II) atom is in a high-spin state and has distorted octahedral surroundings. Distortion of the octahedral polyhedrons appears as axial stretching of the octahedrons along the Co–N bonds; it is due to the specific features of the crystalline structure of the metal polymeric chain in the compounds.

The ability to determine the identity of specific proteins is a critical challenge in many areas of cellular and molecular biology, and in medical diagnostics. Here, we present a macine learning aided microfluidic protein characterisation strategy that within a few minutes generates a three-dimensional fingerprint of a protein sample indicative of its amino acid composition and size and, thereby, creates a unique signature for the protein. By acquiring such multidimensional fingerprints for a set of ten proteins and using machine learning approaches to classify the fingerprints, we demonstrate that this strategy allows proteins to be classified at a high accuracy, even though classification using a single dimension is not possible. Moreover, we show that the acquired fingerprints correlate with the amino acid content of the samples, which makes it is possible to identify proteins directly from their sequence without requiring any prior knowledge about the fingerprints. These findings suggest that such a multidimensional profiling strategy can lead to the development of a novel method for protein identification in a microfluidic format., Protein classification and identification from their multidimensional fingerprints obtained on a microfluidic chip.

A new copper(II) complex (I) was obtained by the reaction of a sterically crowded 2,4-di-(tert-butyl)-9-chloro-benzo[5,6][1,4]oxazine[2,3-b]phenoxazine bridging ligand with Cu(II) hexafluoroacetylacetonate. Compound I is a quasi-one-dimensional complex in which the Cu(hfac)2 moieties are co-crystallized with the triphenodioxazine molecules through only weak Cu⋯N short intermolecular interactions (the Cu⋯N distances are 2.732 and 2.752 A). The magnetic AC susceptibility data show that in spite of the absence of zero-field splitting in the Cu(II) ion with S = 1/2, the compound demonstrates a slow magnetic relaxation behaviour at a weak applied magnetic field (HDC = 500 Oe). The EPR spectra and DC magnetic measurements show the strong axial anisotropy of the g-tensor. The temperature dependence of the relaxation time is well described by the combination of one-phonon direct and two-phonon Raman processes.

In a series of NiFe/Cu/IrMn structures with a variable effective thickness of the nonmagnetic copper interlayer (up to its absence in the NiFe/IrMn sample), we observed a decrease in the exchange bias and coercive force with an increase in the effective thickness of the copper layer. The coalescence of copper islands when the effective thickness of the copper layer reaches 1 nm changes the contact exchange interaction between the ferromagnet and antiferromagnet in NiFe–IrMn to indirect exchange interaction through the conduction electrons of the copper layer in NiFe–Cu–IrMn. The structural quality of single-crystal ferromagnetic and antiferromagnetic layers does not change, and the magnetization reversal occurs without the participation of domains in the temperature range of 2–300 K. Simulation of the deposition dynamics demonstrates the island structure of the film at the initial stages up to an effective thickness of 1 nm.

Specialists in pharmacognosy are facing an important task of improving quality control methods for combination herbal medicinal products in order to enable reliable assessment of the content of active substances that are responsible for the drug’s pharmacological effect.The aim of the study was to investigate the possibility of using the European Pharmacopoeia method to determine the total content of anthracene derivatives in the antihaemorrhoidal medicinal herb mixture Proctophytol® and to propose limit values for the total content of anthracene derivatives.Materials and methods: individual mixture components containing anthracene derivatives, such as senna leaves and frangula bark, as well as model mixtures containing these individual components in a 1:1 ratio, and a model mixture imitating Proctophytol® were used in the study. The determination of the anthracene derivatives content was carried out using spectrophotometry.Results: it was demonstrated that the European Pharmacopoeia method could be used to assess the quality of Proctophytol® in terms of anthracene derivatives total content. The spectrophotometric method described in the European Pharmacopoeia has advantages over the methods described in manufacturer specifications for Russian products, because it allows for thorough extraction of the active substances and is standardized for anthracene derivatives.Conclusions: the European Pharmacopoeia method was adjusted to determine anthracene derivatives in the medicinal herb mixture Proctophytol®. It was proposed to use 70% ethanol instead of 70% methanol as extraction solvent. The authors identified optimum sample weights and test solution dilutions, and calculated and verified the limit for anthracene derivatives content—“Not less than 1.9%”. The adjusted method can be recommended for inclusion in the monographs of the State Pharmacopoeia of the Russian Federation for medicinal herb mixtures similar to Proctophytol®.

In the NiFe/Ta/IrMn structures, the contributions of two types of exchange interactions at the NiFe/IrMn interface, partially separated by sections of the nonmagnetic tantalum interlayer, are distinguished. One type of exchange is “contact”—it occurs directly at the NiFe/IrMn interface. Another type is “interlayer,” which takes place through the conduction electrons of the tantalum interlayer. A comparison of the temperature dependences of the exchange bias of the hysteresis loops at fixed parameters of the ferromagnetic layers and various effective thicknesses of the nonmagnetic interlayer made it possible to separate the contributions of the above types of exchange interactions and determine their temperature dependences individually. The exchange interaction energies at the NiFe/IrMn and NiFe/Ta/IrMn interfaces were determined.

Annealing of a (Pr0.53Dy0.47)12(Fe0.77Co0.23)80B8 (at %) alloy is found to affect the magnetic properties of the sintered magnets fabricated from the alloy. Annealing of the alloy is shown to lead to a 8% increase in the remanence and to nonmonotonic variations of the coercive force by 10–12%. The detected 4% decrease in the dysprosium content in the main magnetic phase and 1% increase in the phase content in the sintered magnet can favor an increase in the residual magnetization. Annealing of the alloy does not lead to changes in the temperature coefficient of induction of the sintered magnets. The diffusion of dysprosium is the most probable cause for the detected changes.

The time changes in the magnetization of the magnets (Pr0.51Dy0.49)13(Fe0.64Co0.36)80B7 and (Pr0.51Dy0.49)13(Fe0.64Co0.36)79Cu1B7 (at %) sintered at 160°C are studied. Alloying of the Pr–Dy–Fe–Co–B materials with copper is shown to cause a decrease in the magnetization losses in time.

A nanonet consisting of ultrathin Ni nanowires (diameter

The humoral immune response plays a key role in suppressing the pathogenesis of SARS-CoV-2. The molecular determinants underlying the neutralization of the virus remain, however, incompletely understood. Here, we show that the ability of antibodies to disrupt the binding of the viral spike protein to the angiotensin-converting enzyme 2 (ACE2) receptor on the cell, the key molecular event initiating SARS-CoV-2 entry into host cells, is controlled by the affinity of these antibodies to the viral antigen. By using microfluidic antibody-affinity profiling, we were able to quantify the serum-antibody mediated inhibition of ACE2–spike binding in two SARS-CoV-2 seropositive individuals. Measurements to determine the affinity, concentration, and neutralization potential of antibodies were performed directly in human serum. Using this approach, we demonstrate that the level of inhibition in both samples can be quantitatively described using the dissociation constants (KD) of the binary interactions between the ACE2 receptor and the spike protein as well as the spike protein and the neutralizing antibody. These experiments represent a new type of in-solution receptor binding competition assay, which has further potential applications, ranging from decisions on donor selection for convalescent plasma therapy, to identification of lead candidates in therapeutic antibody development, and vaccine development.

There is ever increasing evidence that isocitric acid can be used as a promising compound with powerful antioxidant activity to combat oxidative stress. This work demonstrates the possibility of using waste product from the alcohol industry (so-called ester-aldehyde fraction) for production of isocitric acid by yeasts. The potential producer of isocitric acid from this fraction, Yarrowia lipolytica VKM Y-2373, was selected by screening of various yeast cultures. The selected strain showed sufficient growth and good acid formation in media with growth-limiting concentrations of nitrogen, sulfur, phosphorus, and magnesium. A shortage of Fe2+ and Ca2+ ions suppressed both Y. lipolytica growth and formation of isocitric acid. The preferential synthesis of isocitric acid can be regulated by changing the nature and concentration of nitrogen source, pH of cultivation medium, and concentration of ester-aldehyde fraction. Experiments in this direction allowed us to obtain 65 g/L isocitric acid with a product yield (YICA) of 0.65 g/g in four days of cultivation.

Understanding the factors that contribute to antibody escape of SARS-CoV-2 and its variants is key for the development of drugs and vaccines that provide broad protection against a variety of virus variants. Using microfluidic diffusional sizing, we determined the dissociation constant (KD) for the interaction between receptor binding domains (RBDs) of SARS-CoV-2 in its original version (WT) as well as alpha and beta variants with the host-cell receptor angiotensin converting enzyme 2 (ACE2). For RBD-alpha, the ACE2-binding affinity was increased by a factor of ten when compared with RBD-WT, while ACE2-binding of RBD-beta was largely unaffected. However, when challenged with a neutralizing antibody that binds to both RBD-WT and RBD-alpha with low nanomolar KD values, RBD-beta displayed no binding, suggesting a substantial epitope change. In SARS-CoV-2 convalescent sera, RBD-binding antibodies showed low nanomolar affinities to both wild-type and variant RBD proteins—strikingly, the concentration of antibodies binding to RBD-beta was half that of RBD-WT and RBD-alpha, again indicating considerable epitope changes in the beta variant. Our data therefore suggests that one factor contributing to the higher transmissibility and antibody evasion of SARS-CoV-2 alpha and beta is a larger fraction of viruses that can form a complex with ACE2. However, the two variants employ different mechanisms to achieve this goal. While SARS-CoV-2 alpha RBD binds with greater affinity to ACE2 and is thus more difficult to displace from the receptor by neutralizing antibodies, RBD-beta is less accessible to antibodies due to epitope changes which increases the chances of ACE2-binding and infection.

A new binuclear μ-NSC-type nitrosyl iron complex [Fe2(SR)2(NO)4] (R is 5-phenyl-1H-1,2,4-triazole-3-thiolyl) was synthesized. The composition and structure of the newly synthesized complex were determined by atomic absorption, IR, EPR, and Mossbauer spectroscopy and SQUID magnetometry. Amperometric analysis showed that the new complex is an effective nitric oxide (NO) donor in a 1% aqueous DMSO solution. The amounts of NO generated by the complex [Fe2(SR)2(NO)4] in aqueous solutions at physiological pH values were determined. The new complex was shown to have higher antibacterial activity against the gram-positive bacteria Micrococcus luteus compared to kanamycin and streptomycin. According to assays, sulfur-containing ligands of the 1,2,4-triazole-3-thiol series are promising for the design of new antibacterial agents containing the {Fe(NO)2} structural moiety.

(2R,3S)-isocitric acid has long been used only as a specific biochemical reagent. However, there is ever increasing evidence that it can also be used as an original promising substance for prevention and treatment of some diseases. The review considers the results of longtime research in our laboratory and the data of other researchers related to microbial synthesis of (2R,3S)-isocitric acid, derivation and selection of active microbial producers, development of their cultivation conditions, as well as the results of study of the mechanism of acid overproduction, and regulation of enzymes involed in this process. The efficient processes of (2R,3S)-isocitric acid production with the aid of natural, mutant, and recombinant strains of Yarrowia lipolytica and methods of product isolation and purification to pharmacopeial standarts are also reviewed.

Reactions of [Mn(H2 dapsc)Cl2 ]⋅H2 O (dapsc=2,6- diacetylpyridine bis(semicarbazone)) with K3 [Fe(CN)6 ] and (PPh4 )3 [Fe(CN)6 ] lead to the formation of the chain polymeric complex {[Mn(H2 dapsc)][Fe(CN)6 ][K(H2 O)3.5 ]}n ⋅1.5n H2 O (1) and the discrete pentanuclear complex {[Mn(H2 dapsc)]3 [Fe(CN)6 ]2 (H2 O)2 }⋅4 CH3 OH⋅3.4 H2 O (2), respectively. In the crystal structure of 1 the high-spin [MnII (H2 dapsc)]2+ cations and low-spin hexacyanoferrate(III) anions are assembled into alternating heterometallic cyano-bridged chains. The K+ ions are located between the chains and are coordinated by oxygen atoms of the H2 dapsc ligand and water molecules. The magnetic structure of 1 is built from ferrimagnetic chains, which are antiferromagnetically coupled. The complex exhibits metamagnetism and frequency-dependent ac magnetic susceptibility, indicating single-chain magnetic behavior with a Mydosh-parameter φ=0.12 and an effective energy barrier (Ueff /kB ) of 36.0 K with τ0 =2.34×10-11 s for the spin relaxation. Detailed theoretical analysis showed highly anisotropic intra-chain spin coupling between [FeIII (CN)6 ]3- and [MnII (H2 dapsc)]2+ units resulting from orbital degeneracy and unquenched orbital momentum of [FeIII (CN)6 ]3- complexes. The origin of the metamagnetic transition is discussed in terms of strong magnetic anisotropy and weak AF interchain spin coupling.

The process of harmonisation of Russian and foreign approaches and requirements in the field of medicines quality assurance calls for revision of quality control procedures included in various regulations and guidelines. The monograph FS.2.5.0062.18 “Hawthorn flowers” of the State Pharmacopoeia of the Russian Federation XIV edition includes a test procedure for determination of flavonoids by a chromatospectrophotometric method. This procedure does not take into account current scientific capabilities and has a number of shortcomings, therefore it was necessary to revise the existing test procedure and develop a new approach to the standardisation of the hawthorn flower herbal substance.The objectiveof the studywas to develop an assay method for standardisation and evaluation of hawthorn flower using high performance liquid chromatography (HPLC).Materials and methods:the study was performed using samples of hawthorn flowers by Russian manufacturers. Quercetin (USP RS) and Hyperoside (HWI, primary standard) were used as the reference standards. The HPLC analysis was performed using an Infinity II 1260 DAD LC system (Agilent), and the UV spectra were recorded on a Cary 100 Varian spectrophotometer. A TLC Visualizer (CAMAG) was used to obtain digital images of thin layer chromatography plates.Results:the authors developed an HPLC test procedure for quantitative determination of total flavonoids, expressed as hyperoside, in hawthorn flowers. The developed procedure gives reliable and reproducible results and is characterised by high sensitivity and selectivity. The results of quantitative determination of the total flavonoid content in hawthorn flowers were used to propose the standard for the total content of flavonoids, expressed as hyperoside, of “not less than 0.5%”.Conclusions:the developed assay method for determination of active pharmaceutical ingredients in hawthorn flower products by HPLC can be recommended for inclusion into the Assay part of the “Hawthorn Flowers” monograph of the State Pharmacopoeia of the Russian Federation.

The magnetization losses of the (Pr0.51Dy0.49)13.6(Fe0.64Co0.36)79.6B6.8 and (Pr0.51Dy0.49)13.4(Fe0.64Co0.36)78.8Cu1.1B6.7 magnets are studied. The alloying of the Pr–Dy–Fe–Co–B materials with copper is shown to cause a decrease in the magnetization losses in time, which is due to an increase in the coercive force.

—Changes in the magnetic properties of the sintered (Pr0.76Dy0.24)12.9(Fe0.53Co0.47)81.5B5.6 material, which are caused by solid-phase alloying with the (Pr0.63Dy0.37)(Fe0.31Co0.69)2B2 alloy are studied. The dependences of the phase composition and the coercive force of the sintered material on the amount of the added alloy is obtained. As the boron content in the sintered material increases, the content of the main magnetic (Pr, Dy)2(Fe, Co)14B phase decreases from 89.2 to 51.4 vol % and the content of the (Pr, Dy)(Fe, Co)3 phase increases from 7.1 to 43.9 vol %. It was found that, in the course of 190-h storage of sintered magnets in air, their coercive force and density are first unchanged and subsequently decrease; the coercive force decreases to zero.

—The problem of destruction of blanks of ring Nd–Dy–Fe–Co–B magnets with a radial texture and different cobalt and dysprosium contents is considered. The cause of the failure of radial rings after sintering consists in the presence of the (Nd, Dy)(Fe,Co)4B phase, which is characterized by a high linear thermal expansion coefficient. It is shown that the contribution of the (Nd, Dy)(Fe, Co)4B phase to the saturation magnetization can be neglected. The identified phase is found to have a compensation temperature of 100 K.

Background. For the Trans-Urals, characterized by unstable climate over the years (alternating droughty and excessively moist years, recurrences of colds in spring, possibility of early frosts, etc.), grain quality is a prioritized genetic trait in spring bread wheat cultivars. In Kurgan Province, the share of thirdclass wheat varied since 1994 from 43% to 96%; only in the recent unfavorable years (2015 – 2017) it dropped to 11 – 27% due to rust epidemics. The aim of the study was to characterize the genetic potential of grain quality and its phenotypic implementation in promising cultivars bred at Kurgan Agricultural Research Institute and officially released for cultivation in the region.Materials and methods. The capacities of the KASIB4 – 13 (Kazakhstan–Siberia Wheat Improvement Network under the auspices of CIMMYT) represented by 17 breeding centers in Kazakhstan and Siberia were used to assess grain quality of 14 cultivars with different maturation time bred at Kurgan Agricultural Research Institute. Quality assessment was performed with due regard to the standards of Kazakhstan, CIS, and leading exporting countries, thus combining local and international levels, and employing genetic, biochemical and technological grain quality levels under different soil and climate conditions.Results and discussion. Generally, all cultivars demonstrated protein and gluten content and the level of vitreousness sufficient for strong and valuable wheat. The selected percentage was 92% for hard grain and medium hard grain wheat forms, up to 94% for high-protein and high-gluten ones, and up to 57% for genotypes without 1B/1R wheat/rye translocation. In terms of sedimentation, 86% of the genotypes were predicted to belong to the strong and valuable wheat class; according to the composition of HMW glutenin subunits, mixing quality and flour strength (W), 30 – 42% were identified as high-quality genotypes. The in-depth study of grain quality within the KASIB environmental network revealed heterogeneity among cultivars in a number of genetic and biochemical parameters and provided an opportunity to select high-quality genotypes by marker characteristics and technological properties, which is likely to improve the efficiency of intra-cultivar selection and overall quality assessment of cultivars.

The effect of copper alloying on the coercive force and the residual induction of sintered materials (Pr0.53Dy0.47)13(Fe0.64Co0.36)resCuxB6 (x = 0–3 at %) annealed at various temperatures is considered. The dependences of coercive force HcI and residual induction Br on the copper content are found to be nonmonotonic. This fact is explained by that alloying with copper leads to a change in the phase composition, which is accompanied by an increase in the coercive force and the residual magnetization of the alloy, while a change in the chemical composition and the thickness of intergranular interlayers upon copper alloying leads to a decrease in the values of HcI and Br as the copper content increases.

New method for the synthesis of the mononuclear anionic iron dinitrosyl complexes (DNICs) as prospective agents for nitric oxide (NO) chemotherapy of oncological diseases has been developed. Mononuclear anionic DNIC of the composition (N2H5)+[Fe(SR)2(NO)2]- with R = 5-nitropyridinyl (I) has been synthesized by the reaction of aqueous solutions of Na2[Fе(S2O3)2(NO)2] and N2H5[SС5H3N2O2] salts. The latter one was synthesized by the reduction of bis-(5-nitro-pyridin-2-yl) disulfide with hydrazine hydrate in ethanol at T = 25 °C. Physical-chemical properties of the synthesized complex were studied by X-ray, SEM, IR-, EPR, Mossbauer spectroscopy and SQUID magnetometry in combination with DFT quantum-chemical calculation of molecular structure and spectroscopic properties. Complex I was found to generate NO in proton media without additional activation. The cytotoxicity of I to human tumor cells of various geneses, viz. ovarian cancer SKOV3, colon cancer LS174T and non-small cell lung cancer A549 was discovered for the first time.

Biosynthesis of Ds(+)-threo-isocitric acid from ethanol in the Yarrowia lipolytica batch and repeated-batch cultures was studied. Repeated-batch cultivation was found to provide for a good biosynthetic efficiency of the producer for as long as 748 h, probably due to maintenance of high activities of enzymes involved in the biosynthesis of isocitric acid. Under optimal repeated-batch cultivation conditions, the producer accumulated 109.6 g/L Ds(+)-threo-isocitric acid with a production rate of 1.346 g/L h. The monopotassium salt of isocitric acid isolated from the culture liquid and purified to 99.9% was found to remove neurointoxication, to restore memory, and to improve the learning of laboratory rats intoxicated with lead and molybdenum salts. Taking into account the fact that the neurotoxic effect of heavy metals is mainly determined by oxidative stress, the aforementioned favorable action of isocitric acid on the intoxicated rats can be explained by its antioxidant activity among other pharmacological effects.

Sintered (Pr0.53Dy0.47)ΣR(Fe0.77Co0.23)balB7.5 materials are studied. For the Nd–Fe–B-based materials, the calculated neodymium content in the Nd2Fe14B compound is 11.8 at %, whereas an excess neodymium content as compared to that for the stoichiometric composition should be taken for manufacturing magnets. In contrast to the magnets based on the aforementioned system, the magnets based on the Pr–Dy–Fe–Co–B system can be prepared at a lower total rare-earth metal content as compared to that corresponding to the stoichiometric composition. Magnets with a coercive force of 528 kA/m are manufactured at a total rare-earth metal content of 11.5 at %, which is lower than that calculated for the R2(Fe, Co)14B (R = Pr, Dy) phase.

Periodical transformation of ferroin to ferriin is accompanied by changes in magnetic properties of liquids during Belousov&ndash, Zhabotinsky (BZ) reaction malonic acid, sodium bromide, sodium bromate, ferroin, and sulfuric acid. Instead of the earlier studied oscillation of microwave conductivity accompanying an oscillating reaction, we propose a flash technique to interrupt the BZ reaction by rapid freezing. Rapid cooling of a solution during chemical oscillations results in a frozen system with a fixed concentration of paramagnetic centers Fe3+. EPR spectrum recorded at different stages of the interrupted reaction corresponds to the exact concentration of the ferroin and ferriin components. Following unfreezing unblocks the BZ reaction, and oscillations are still observed. A simulated spectrum allows one to distinguish two groups of Fe3+ ions of different symmetries. The obtained results are important to explain the earlier observed effect of inhomogeneous magnetic field on BZ reaction front velocity.

The humoral immune response plays a key role in suppressing the pathogenesis of SARS-CoV-2. The molecular determinants underlying the neutralization of the virus remain, however, incompletely understood. Here, we show that the ability of antibodies to disrupt the binding of the viral spike protein to the angiotensin-converting enzyme 2 (ACE2) receptor on the cell, the key molecular event initiating SARS-CoV-2 entry into host cells, is controlled by the affinity of these antibodies to the viral antigen. By using microfluidic antibody-affinity profiling, we were able to quantify the serum-antibody mediated inhibition of ACE2–spike binding in two SARS-CoV-2 seropositive individuals. Measurements to determine the affinity, concentration, and neutralization potential of antibodies were performed directly in human serum. Using this approach, we demonstrate that the level of inhibition in both samples can be quantitatively described using the binding energies of the binary interactions between the ACE2 receptor and the spike protein, and the spike protein and the neutralizing antibody. These experiments represent a new type of in-solution receptor binding competition assay, which has further potential areas of application ranging from decisions on donor selection for convalescent plasma therapy, to identification of lead candidates in therapeutic antibody development, and vaccine development.

Herein, we report the synthesis and magnetic properties of the Co(II) coordination compound with the 1,1′-bis(1-((pyrid-2-ylmethylene)hydrazono)ethyl)ferrocene (L) ligand, having the general formula [CoLCl2]. The static magnetic data analysis supported by the CASSCF/NEVPT2 calculations revealed the presence of the triaxial magnetic anisotropy with Dexp = +35.2 cm−1 and large rhombicity (E/D = 0.31) in this complex (Dcalc = +34.5 cm−1, E/Dcalc = 0.30). The dynamic magnetic data confirm that the complex shows a slow field-induced (HDC = 1000 Oe) magnetic relaxation behaviour.

Magnetocaloric effect (MCE) in an antiferromagnetic holmium (Ho) film is studied near the spin reorientation temperatures. A series of magnetization isotherms from 60 to 150 K around the N\'eel temperature, ${T}_{N}\ensuremath{\approx}130\phantom{\rule{0.28em}{0ex}}\mathrm{K}$ were recorded for both in-plane and out-of-plane magnetic field orientations. A change in entropy, $\mathrm{\ensuremath{\Delta}}{S}_{M}$ of $\text{--}5\phantom{\rule{0.28em}{0ex}}\mathrm{J}/\mathrm{kg}\mathrm{K}$ was found near ${T}_{N}$ for an in-plane field orientation. A large change in $\mathrm{\ensuremath{\Delta}}{S}_{M}$ of \ensuremath{-}11.8 J/kg K due to a fan-helix spin transition at $T=90\phantom{\rule{0.28em}{0ex}}\mathrm{K}$ is observed for an in-plane field orientation. Spin transition at both ${T}_{N}$ and at the fan-helix transition exhibit larger MCE in the in-plane field orientations in comparison with the perpendicular orientation. The value of the refrigerant capacity extracted from the temperature dependence of $\mathrm{\ensuremath{\Delta}}{S}_{M}(T)$ is found to be larger for the ``in- plane'' orientation by a factor of two.

This work demonstrates the ability of the yeast Yarrowia lipolytica cultivated on biodiesel waste to synthesize α-ketoglutaric acid with a minimal content of pyruvic acid as the main byproduct. The key factor promoting the microbial production of α-ketoglutaric acid from the waste is a strong deficiency of thiamine in the cultivation medium. The production of α-ketoglutaric acid by the yeast can be regulated by changing the concentration of nitrogen, iron, zinc, copper, and manganese in the medium, as well as by pH medium and the aeration rate. The optimization of these parameters in flask experiments allowed us to increase the concentration of α-ketoglutaric acid in the medium by 2.6 times and to shift the α-ketoglutaric acid/pyruvic acid ratio from 5:1 to 30:1. During cultivation in a fermentor under optimized conditions, Y. lipolytica produced 80.4 g/L α-ketoglutaric acid with a process selectivity of 96.7% and the product yield (YKGA) equal to 1.01 g/g. • α-Ketoglutaric acid is commercially important biotechnological product. • Biosynthesis of α-ketoglutaric acid from biodiesel waste. • Optimization of cultivation medium and nutrition medium.

Within this work, the microbial synthesis of (2R,3S)-isocitric acid (ICA), a metabolite of the nonconventional yeast Yarrowia lipolytica, from biodiesel waste, has been studied. The selected strain Y. lipolytica VKM Y-2373 synthesized ICA with citric acid (CA) as a byproduct. This process can be regulated by changing cultivation conditions. The maximal production of ICA with the minimal formation of the byproduct was provided by the use of a concentration of (NH4)2SO4 (6 g/L), the addition of biodiesel waste to cultivation medium in 20&ndash, 60 g/L portions, maintaining the pH of the cultivation medium at 6, and degree of aeration between 25% and 60% of saturation. Itaconic acid at a concentration of 15 mM favorably influenced the production of ICA by the selected strain. The optimization of cultivation conditions allowed us to increase the concentration of ICA in the culture liquid from 58.32 to 90.2 g/L, the product yield (Y) by 40%, and the ICA/CA ratio from 1.1:1 to 3:1. Research on laboratory animals indicated that ICA counteracted the negative effect of ammonium molybdate (10&minus, 5 М) and lead diacetate (10&minus, 7 М) on the learning and spatial memory of rats, including those exposed to emotional stress.

Background In previous publications, we have proposed new algorithm of pharmacologic Stress Echo with possibility of stepwise adenosine triphosphate (ATP) i/v dose increase (Figure 1). Purpose In this study we decided to compare the effectiveness of detection of symptom related coronary arteries in patients with coronary artery disease (CAD) by ATP 4D Stress Echo of left ventricle (LV) and a) traditional visual evaluation of LV segmental hypokinesis b) Automatic Function Imaging (AFI) technology longitudinal LV strain (LS) analysis. Material and methods. 26 patients with CAD (male 24, mean age 63.1 ± 7.5 years, single vessel obstructive disease 7, multivessel - 19) underwent ATP LV 4D Stress Echo (Vivid E95, GE). Number of cases when it was possible to detect symptom related arteries by visual analysis of LV segmental hypokinesis and by AFI LV LS analysis were compared. Results In 11 (42.3%) patients expansion of existing hypokinetic areas and appearance of new LV segments with hypokinesis during stress test were detected by visual analysis. Using AFI technology expansion of initial areas of LS disturbances and appearance of new LV segments with LS disturbances were found in 21 (80,7%) patients (р=0.0044). Conclusion Utilization of AFI LV LS analysis during ATP LV 4D Stress Echo significantly increases the frequency of symptom related coronary arteries detection in patients with CAD. Abstract P1550 Figure1

The use of assay methods with different test conditions for determination of anthracene derivatives in herbal substances and herbal medicinal products requires adjustment of the established limits for total anthracene derivatives content based on the test method used.The aimof the study was to compare different pharmacopoeial methods of quantitative determination of anthracene derivatives, and established limits for the active substance content, and to analyse the possibility of adjusting the limits based on the test method used.Materials and methods: the total content of anthracene derivatives was measured in the samples of frangula bark (fragmented bark and powder) and senna leaves (fragmented leaves and powder) using the test methods described in the State Pharmacopoeia of the Russian Federation (XI and XIII editions), and the European Pharmacopoeia.Results:the analysis of Russian and foreign pharmacopoeial requirements for determination of anthracene derivatives in laxative herbal medicinal products demonstrated differences in extraction solvents, extraction conditions, and calculation methods used. The experiments showed that the optimal extraction solvent was 70 % alcohol solutions, and that an indirect cobaltic chloride reference standard should be replaced by specific absorbance of glucofrangulin A and sennoside B. It was shown that the limits for total anthracene derivatives content should be chosen based on the extraction conditions used.Conclusions:comparative theoretical research and experimental studies helped to determine optimal assay conditions and respective limits for total anthracene derivatives content to be used in quality control of herbal substances and herbal medicinal products.

The ability of different yeasts to synthesize pyruvic acid (PA) from glycerol-containing substrates has been studied. The selected strain Yarrowia lipolytica VKM Y-2378 synthesized PA with α-ketoglutaric acid (KGA) as a byproduct. The content of KGA greatly depended on cultivation conditions. The minimal formation of the byproduct was provided by the limitation of yeast growth by thiamine (0.6 µg/g biomass); the use of ammonium sulfate (0.6%) as a nitrogen source; addition of glycerol to cultivation medium in 20 g/L portions; maintaining the cultivation temperature at 28 °C, pH of the cultivation medium at 4.5, and medium aeration between 55 and 60% of saturation; the optimal cultivation time was 48 h. The selected strain cultivated under such conditions in a fermenter with a waste glycerol from biodiesel production process synthesized 41 g/L PA with a yield of 0.82 g/g. The mechanism of PA production from glycerol-containing substrates in Y. lipolytica is discussed.

Homogeneous composites based on poly(methyl methacrylate) and its copolymers with methacrylic acid and on the nitrosyl iron complexes with 2-mercaptobenzimidazole and 2-mercaptobenzthiazole were synthesized. An analysis of the experimental data obtained by the methods of small-angle X-ray diffraction and SQUID magnetometry in combination with the results of quantum chemical calculations showed that the nitrosyl complexes did not retain their initial binuclear structure under the matrix isolation conditions: some complexes decompose to mononuclear ones. The percentage ratio of the dimers and monomers depends on the fraction of the methacrylic acid copolymer in the polymeric matrix and is almost independent of the type of thiol ligand in the iron complex.

The construction of an electret stimulator of osteoreparation (ESO) made of tantalum with an anodic oxide (AO) surface in the electret state (ES) is described. Factors leading to degradation of the ES of AO were investigated and recommendations for preventing this during manufacture, storage, and use of the ESO were developed. A polarization mechanism for propagating the effects of the electret electric field to all the main structures of the device is proposed.

The effect of the electric field of a medical electret on the basis of tantalum pentoxide (Ta2O5) on the viability of human fibroblasts, multipotent mesenchymal stromal bone marrow cells, osteocytes, and chondrocytes cultivated on the surface of tantalum orthopedic implants with an electret coating was studied in vitro. Using the methods of photocolorimetic analysis and scanning electron microscopy, difference in the metabolic activity and cell morphology, in the character of the cell attachment to the implants and distribution by their surface, associated with the value and character of the electric charge distribution on the surface of these implants and the type of cellular test systems, were detected. Unclear mechanisms of the effect of the electric field of medical electrets on the functional activity of different types of the organism cell and tissues dictate the need for further experimental developments and fundamental studies in this field.