Thermosensitive and Wound-Healing Gelatin-Alginate Biopolymer Hydrogels Modified with Humic Acids

The main goal of the article is the creation and study of thermosensitive and wound-healing gelatin-alginate bio-polymer hydrogels modified with humic acids.Their rheological properties,swelling and contraction behavior were experimentally investigated,elucidated using Fourier transform infrared spectroscopy and used to achieve the physiological melting point,which is necessary for successful drug delivery.It has been shown that in the gelatin-alginate-humic acid biopolymer hydrogels systems,it is possible to obtain a gel-sol transition temperature close to the physiological temperature of 37℃,which is important for drug delivery in the treatment of wounds.By changing the type and concentration of humic acids in the gelatin-alginate hydrogel,it turned out to be achiev-able to regulate the softening time of the gel on the human body in the range from 6 to 20 min,which provides the possibility of controlled prolonged delivery of drugs.Based on the study of the influence of calcium ions on the properties of humic acids and ion exchange,as well as the interaction of humic acids,sodium alginate and gelatin with the formation of tighter gel networks,approaches to regulate the rate of softening of hydrogels at physiological temperature and their swelling,which simulates the absorption of exudate,were proposed and implemented.In addition,low shrinkage of the hydrogel surface due to cross-linking of gelatin-alginate networks when modified with humic acids was experimentally confirmed,which is important for avoiding problems of wound contracture and contour deformations when using dressings for wound healing.Thus,the developed opti-mized innovative biopolymer hydrogels synergistically combine the outstanding properties of natural molecular polymers and humic acids and are promising for the creation of effective medicines for wound healing.

Human chemerin induces eryptosis at concentrations exceeding circulating levels

Introduction:Human chemerin is an adipokine that regulates chemotaxis,inflammation,and glucose metabolism.In addition,accumulating evidence suggests that chemerin promotes apoptosis,autophagy,and pyroptosis.However,there are no data on its impact on eryptosis.The current study aimed to analyze the effects of human active Glu^(21)-Ser^(157) chemerin on eryptosis in vitro.Materials and Methods:Human chemerin 0-2-10-50μg/mL was incubated for 24 h with human erythrocytes(hematocrit 0.4%)obtained from eight healthy individuals.Flow cytometry-based determination of phospholipid scrambling,reactive oxygen species(ROS)production,and intracellular Ca^(2+)levels was performed.To supplement data on ROS and Ca^(2+)signaling in chemerin-mediated eryptosis,incubation in the presence or absence of antioxidants vitamin C and N-acetylcysteine and Ca^(2+)-binding agent EGTA was carried out,respectively.Confocal microscopy-based techniques were used to detect reactive nitrogen species(RNS)generation,involvement of caspase-3 and caspase-8,as well as the state of lipid order in cell membranes of erythrocytes exposed to human Glu^(21)-Ser^(157) chemerin.Results:Our observations suggest that human Glu^(21)-Ser^(157) chemerin had no impact on eryptosis parameters at 2μg/mL.However,chemerin stimulated phosphatidylserine externalization,ROS production,and Ca^(2+)accumulation at higher concentrations suggesting activation of eryptosis.Ca^(2+)uptake turned out to be at least partly required for chemerin-mediated eryptosis.Chemerin-mediated erythrotoxicity was additionally mediated by RNS,caspase-3,and caspase-8.Moreover,Glu^(21)-Ser^(157) chemerin promoted reduction in the liquid-ordered phase of cell membranes in erythrocytes.Conclusions:The present study first discloses that human chemerin can induce eryptosis via Ca^(2+)-dependent mechanisms at concentrations noticeably exceeding circulating levels.Thus,chemerin-induced eryptosis can hardly contribute to eryptosis-mediated anemia in diseases associated with enhanced levels of chemerin in blood.

Berberine Prolongs Life Span and Stimulates Locomotor Activity of <i>Drosophila melanogaster</i>

Drosophila melanogaster mutants with deficient kynurenine (KYN) formation from tryptophan (TRP) have longer life span than wild type flies. Administration of alpha-methyl-TRP and 5-methyl-TRY, the inhibitors of TRP-KYN metabolism, prolonged life span in wild-type flies. Both inhibitors are not available for human use. Berberine, an isoquinoline alkaloid isolated from berberis aristata is known as the herb widely used in traditional Chinese and Indian medicine. Berberin is a strong inhibitor of the enzyme catalyzing TRP conversion into KYN. Considering this particular feature we investigated the effect of berberine on life-and health-span in wild-type Drosophila melanogaster. The results of our study showed that Berberine extended mean, median and maximum life span of female flies. Berberine did not affect the number of pupae of filial generation and decreased their lethality. Berberine increased locomotor activity (vertical climbing). The results of the study suggest that berberine prolongs life- and improves health-span of Drosophila melanogaster. Berberine might be a candidate drug for prevention and treatment of aging and aging-associated medical and psychiatric disorders.

Berberine Attenuated Aging-Accelerating Effect of High Temperature in Drosophila Model

We have observed that berberine prolonged life span and improved viability of pupae and climbing activity of imagoes of wild-type Drosophila melanogaster maintained at 23°C. As a continuation of our studies of berberine effect on life span, we were interested to evaluate the effect of berberine of life span in flies maintained at a higher temperature (28°C) known to accelerate aging in wild type flies. Considering that genetically or pharmacologically induced deficiency of TRP conversion into KYN prolonged life span in a Drosophila model, we compared the effects of berberine, a powerful inhibitor of kynurenine (KYN) formation from tryptophan (TRP), on life span in wild type and in Drosophila melanogaster mutants (vermilion) with deficient TRP-KYN metabolism maintained at 23°C and 28°C. High (28°C) ambient temperature decreased life span in both wild type and vermilion flies. Aging accelerating effect of high temperature was more pronounced in Oregon than in vermilion flies (-60% vs. -40% decrease of mean life span, resp). Berberine attenuated the aging-accelerating effect of high temperature. Effect of berberine was more pronounced in Oregon (+46%) than in vermilion (+22%) flies. The obtained data suggested the possible involvement of TRP-KYN metabolism in the aging-acceleration effect of the high temperature and in protective effect of berberine.

World cities in terms of the sustainable development concept

The article considers the issue of the world cities in terms of sustainable development.The population has been increasing in such intensive rates never reached during the middle of the 20th century.The expansion of the cities indicates,on the one hand,the growth of the world’s general socio-economic development,on the other hand,it raises a number of economic,social and environmental problems.The purpose of this paper is to analyze the current state and prospects of the world cities in terms of the sustainable development concept,to identify opportunities,threats,strengths and weaknesses of the world cities,to determine the role of cities in the con-temporary global world and consider further research of the world’s cities.The authors analyzed the world cities rankings and noted that highly developed cities have more chances to quickly implement the sustainable devel-opment concept compared to medium-sized cities due to larger financial resources.The authors built a SWOT analysis of the world cities transformation in terms of the sustainable development concept,identified strengths,weaknesses,opportunities and threats.According to the results of the SWOT analysis,the authors established that sustainable development of cities requires significant investments,particularly in the social sphere develop-ment,purification,and preservation of urban nature from the anthropogenic impacts.The research result is the systematization of the sustainable development criteria used in compiling the world cities rankings,determining the possibilities of the contemporary cities transition to the sustainable development concept.

Nonlinear Vortex Structures in Obliquely Rotating Fluid

In this paper, we find a new large scale instability which appears in obliquely rotating flow with the small scale turbulence, generated by external force with small Reynolds number. The external force has no helicity. The theory is based on the rigorous method of multi-scale asymptotic expansion. Nonlinear equations for instability are obtained in the third order of the perturbation theory. In this article, we explain in detail the nonlinear stage of the instability and we find the nonlinear periodic vortices and the vortex kinks of Beltrami type.

Frequency drift rate of solar decameter"drift pair"bursts

This paper deals with the detailed analysis of frequency drift rates of solar ＂drift pair＂ （DP） bursts observed from 2015 July 10 to 12 during a type III burst storm. The observations were conducted by the UTR-2 radio telescope at 9-33 MHz with high frequency and time resolution. DPs were recorded drifting from higher to lower frequencies （forward DPs） as well as from lower to higher ones （reverse DPs）. Patterns on their dynamic spectrum had various inclines and occupied different bandwidths. The frequency drift rate versus frequency dependence of these bursts has been studied. The fitting model to describe the peak evolution of these bursts in the frequency-time plane is presented. The relationship between DPs and type III solar bursts is discussed.

The first detection of the solar U+Ⅲ association with an antenna prototype for the future lunar observatory

We report about observations of solar U+Ⅲ bursts on 2020 June 5 by means of a new active antenna designed to receive radiation in 4–70 MHz.This instrument can serve as a prototype of the ultralong-wavelength radio telescope for observations on the farside of the Moon.Our analysis of experimental data is based on simultaneous records obtained with the antenna arrays GURT and NDA in high frequency and time resolution,e-Callisto network as well as by using the space-based observatories STEREO and WIND.The results from this observational study confirm the model of Reid and Kontar.

Nonequidistant two-dimensional antenna arrays based on Latin squares

Non-equidistant sparse antenna arrays constructed on the basis of Latin squares are considered. A method for their construction and a synthesis algorithm are proposed,and the properties of two-dimensional antennas based on them,which ensure,at a high degree of rarefaction,a sufficiently small lateral radiation are studied. The features and main characteristics of such antennas are studied.

Bone Marrow Cells Obtained from Old Animals Differ from the Young Animals Cells in Their Ability to Divide and in Response to the Presence of Liver Fibrosis in Primary Culture

Dynamics of bone marrow cells number (BMC) in the primary culture isolated from young (3 months) and old (20 months) Wistar rats was investigated. Proliferative activity of BMC of old animals was 2 times higher than that of young animals in the primary culture. Such superiority of the proliferative activity of BMC in the primary culture obtained from old animals is associated with the ability to actively divide lymphocytes and longer “lifespan” of segmented neutrophils obtained from old animals. It should be noted, that the lymphocytes of young animals did not proliferate in the primary culture. The content of intracellular calcium in BMC in the cells of old animals was 3 times higher compared with cells of young animals, which revealed the relationship of intracellular calcium and proliferative activity of BMC. Induction of liver fibrosis led to an increase in the lymphocyte content in young animals by 167%, and in old ones only by 26%, while the lymphocytes of young animals acquired the ability to proliferate in the primary culture. It has been suggested that such differences in the behavior of BMC in primary culture obtained in young and old animals reflect differences in the BMC microenvironment of young and old animals, which leads to changes in the epigenetic-metabolic characteristics of BMC.

Development of Biotechnology for Microbial Synthesis of Gold and Silver Nanoparticles

Several bacterial strains of Actinomycetes belonging to Streptomyces and Arthrobacter genera for the first time were used to study the biotechnology of synthesis of gold and silver nanoparticles. The experimental conditions of gold and silver nanoparticles production by the cells of studied strains in aqueous chloroauric acid （HAuCIq） and in silver nitrate （AgNO3） solutions, respectively, were determined. Concentration and time-dependences of nanoparticle formation were investigated. The complex of optical and analytical methods was used for testing the gold and silver nanoparticles in the bacterial biomass. The TEM （Transmission Electron Microscopy） and XRD （X-ray Diffraction） data in all cases demonstrated the presence of crystals with fcc （face centered cubic） structure. The results obtained show that the Actinomycetes are capable of producing gold and silver nanoparticles of spherical shape extracellularly when exposed to suitable compounds. The particle size distribution shows that the sizes of nanoparticles are in the range of 5 nm to 80 nm. The biomass obtained may be used for industrial as well as medical and pharmaceutical purposes.

A Frank-Read Source Model

The temporal dynamics of the edge dislocation (ED) was studied in this work using the inhomogeneous dissipative sine-Gordon (SG) equation. The consideration was carried out for the force action levels both less and more critical. By SG equation numerical calculations it is shown that at the external force value below a critical one the ED takes a shape close to a semicircle. This shape was used as an initial condition for describing the ED temporal dynamics in the FR source operating mode. A particular solution of the SG equation is proposed that describes the temporal dynamics of half the ED in the FR mode, which rests on a stopper at the origin. It is shown that the proposed particular solution corresponds to the left Archimedes spiral displaced at π/2 counterclockwise relative to the azimuth angle equal to zero. It is noted that the temporal dynamics of the second half of the ED segment rested on the second stopper is described by the proposed particular solution, when it is mirrored relative to the problem symmetry axis and the center of the spiral is displaced to a point with a zero azimuthal angle and a radius equal to the distance between the stoppers. The axis of symmetry is a straight line that is perpendicular and halves the distance between the stoppers. A graphical description of the ED temporal dynamics was plotted in the Cartesian coordinate system based on the proposed particular solution and its mirror and displaced image. It is shown that the particular solution of the SG equation in the RF source operation mode involves two Archimedes spirals symmetrical relative to the problem symmetry axis with equal radii increasing linearly with time, which rotate: one (the spiral center coincides with the stopper at the origin) counterclockwise, the second (the spiral center coincides with the second stopper) clockwise.

Decentralized Proof-of-Burn auction for secure cryptocurrency upgrade

We propose a new approach for a secure,decentralized,and censorless upgrade of existing cryptocurrencies to newly created tokens without interaction with any external information sources(oracles).The proposed scheme is based on the burning of existing cryptocurrency tokens and implemented via the multi-currency auction.The auction is carried out on the blockchain of the new token and implemented using a smart contract that processes participants’bids of burnt tokens of other cryptocurrencies and supports a new token price discovery algorithm for each cryptocurrency with no oracles or any other trusted source of information.Contrary to traditional ways of getting the new asset,like centralized and decentralized exchanges,our method requires no user registration(as well as no KYC-“know your customer”procedure that requires obligatory client identification)and provides a predicted supply level of the new asset for an adequate price within a model with economically rational participants.We provide the results of decentralized auction simulations implemented for several strategies of user behavior(based on bid prices with normal and log-normal distribution laws),both under the normal operation and in the presence of an adversary who follows specific strategies.

Zingiber officinale extends Drosophila melanogaster life span in xenobiotic-induced oxidative stress conditions

BACKGROUND： The possibility of dietary ginger to enhance oxidative stress resistance and to extend life span was studied on Drosophila melanogaster. METHODS： Oxidative stress was induced by a reducing agent dithiothreitol. Experimental groups of male D. melanogaster were cultured on media containing： 1） no additive; 2） dithiothreitol, added into the nutritional mixture to the final concentration of 10 mM; 3） 25 mg of ginger powder g^-1 of the nutritional mixture; and 4） 10 mM ofdithiothreitol and 25 mg of ginger powder g l of the nutritional mixture. The number of alive fruit flies was inspected daily, and mean life span was determined for each experimental group. RESULTS： The addition of dithiothreitol to D. melanogaster nutritional mixture was established to result in an increase in concentration of two markers of oxidative stress conditions （thiobarbituric acid reactive substances as products of lipid peroxidation and carbonylated proteins as products of protein oxidation） in fly tissues. It was followed by significant reduction of mean life span and maximum life span of the last 10% of flies. Plant preparation, being added simultaneously with dithiothreitol, significantly diminished the negative effects of this xenobiotic. In conditions of additional stress load induced by hydrogen peroxide or high temperature, survival of insects treated with dithiothreitol on the background of ginger powder was the highest. CONCLUSIONS： Thus, the presented data give the evidence that ginger preparations can reduce oxidative stress outcomes and significantly increase the life expectancy of fruit flies in stress conditions.

Singular integrals in axisymmetric problems of elastostatics

Singular integral equations arisen in axisymmetric problems of elastostatics are under consideration in this paper.These equations are received after applying the integral transformation and Gauss-Ostrogradsky’s theorem to the Green tensor for equilibrium equations of the infinite isotropic medium.Initially,three-dimensional problems expressed in Cartesian coordinates are transformed to cylindrical ones and integrated with respect to the circumference coordinate.So,the three-dimensional axisymmetric problems are reduced to systems of one-dimensional singular integral equations requiring the evaluation of linear integrals only.The thorough analysis of both displacement and traction kernels is accomplished,and similarity in behavior of both kernels is established.The kernels are expressed in terms of complete elliptic integrals of first and second kinds.The second kind elliptic integrals are nonsingular,and standard Gaussian quadratures are applied for their numerical evaluation.Analysis of external integrals proved the existence of logarithmic and Cauchy’s singularities.The numerical treatment of these integrals takes into account the presence of this integrable singularity.The numerical examples are provided to testify accuracy and efficiency of the proposed method including integrals with logarithmic singularity,Catalan’s constant,the Gaussian surface integral.The comparison between analytical and numerical data has proved high precision and availability of the proposed method.