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Nonmagnetic impurity scattering is known to shift up the Ginzburg–Landau parameter κ of a superconductor. In this case, when the system is initially in type I, it can change its magnetic response, crossing the intertype domain with κ ∼ 1 between the two standard superconductivity types and arriving at type II. In the present work we demonstrate that the impact of disorder can be much more profound in the presence of the multiband structure of the charge carrier states. In particular, when the band diffusivities differ from each other, the intertype domain tends to expand significantly, including points with κ ≫ 1 that belong to deep type-II in conventional single-band superconductors. Our finding sheds light on the nontrivial disorder effect and significantly complements earlier results on the enlargement of the intertype domain in clean multiband superconductors. [ABSTRACT FROM AUTHOR]

The combination of strongly coupled Cooper pairs and weak superconducting fluctuations is an important prerequisite for achieving high-temperature superconductivity. The review is devoted to the implementation of this condition in multiband superconductors, in which strongly coupled pairs in the shallow conduction band (the Fermi level is close to the band edge) coexist with ordinary, weakly fluctuating Cooper pairs formed in the deep band. As a result of the Josephson coupling between condensates in different bands, such a system is characterized by a high critical coherence temperature due to the presence of strongly coupled pairs and the suppression of superconducting fluctuations. This suppression does not require any special preconditions, and is almost total even if the Josephson coupling between the bands is weak. [ABSTRACT FROM AUTHOR]

In many pnictides the superconductivity coexists with ferromagnetism in an accessible range of temperatures and compositions. Recent experiments revealed that when the temperature of magnetic ordering Tm is below the superconducting transition temperature Tc, highly non-trivial physical phenomena occur. In this work we demonstrate the existence of a temperature window, situated between Tm and Tc, where these intrinsically type-II superconductors are in the intertype regime. We explore analytically and numerically its rich phase diagram characterized by exotic spatial flux configurations—vortex clusters, chains, giant vortices and vortex liquid droplets—which are absent in both type-I and type-II bulk superconductors. We find that the intertype regime is almost independent of microscopic parameters, and can be achieved by simply varying the temperature. This opens the route for experimental studies of the intertype superconductivity scarcely investigated to date. The interplay between ferromagnetism and superconductivity plays an important role in trying to understand the mechanisms of superconductivity in iron-based pnictides. Here, the authors investigate a phenomenon called intertype superconductivity which appears due to a crossover from type II to type I between the superconducting transition temperature and magnetic ordering one. [ABSTRACT FROM AUTHOR]

The intestinal microbiota is known to perform an important role in terms of the host organism's metabolism and life-sustaining activities. One of the main mechanisms of the interactions between microbiota and the human organism is based upon biogenic amines (BAs). Therefore, BA synthesis by lactic acid bacteria (LABs) is extensively researched currently, and the BA-forming capacity is considered an essential feature of LAB probiotics. The present work is concerned with BA production by 13 strains of three LAB species that were isolated from various habitats. They perform diverse ecophysiological functions and were grown on four different media. The media were characterized by different initial BA concentrations. It was established that the LABs could both consume BAs present in the medium and synthesize them de novo during their growth. The data should be taken into account while developing new probiotics. Based on the results of this work, a modified version of BA biosynthesis pathways by LABs was suggested. This work also deals with the implications of the data obtained in terms of the involvement of microbially produced neuroactive compounds in the functioning of the microbial consortium of the human organism and the operation of human nervous and the immune systems. Prospects for developing "neurotransmitters-producing biofactories" on the basis of the tested symbiotic and probiotic microorganisms are discussed. [ABSTRACT FROM AUTHOR]

Fungi Eurotium spp. are the main biological agents that ferment the leaves of the Camellia sinensis tea bush to form a popular food product, postfermented tea. The fungus E. cristatum, stored in the collection of the Gause Institute of New Antibiotics under the number INA 01267, was isolated and identified from a briquette of Fujian Chinese tea. The species identification was carried out based on morphocultural characteristics and DNA sequencing. This study is aimed at determining the feasibility of making postfermented herbal teas using E. cristatum and to evaluate their quality. Autofermented herbal teas from Chamaenerion angustifolium (fireweed) and Malus domestica (apple tree) served as the starting material for this study. The change in the concentration of phenolic compounds, organic acids, sugars, and free amino acids was observed for herbal teas subjected to postfermentation with E. cristatum INA 01267. It was found that the E. cristatum INA 01267 strain does not have antimicrobial activity and does not form mycotoxins, which is an indicator of food safety. [ABSTRACT FROM AUTHOR]

Fungi Eurotium spp. are the main biological agents that ferment the leaves of the Camellia sinensis tea bush to form a popular food product, postfermented tea. The fungus E. cristatum, stored in the collection of the Gause Institute of New Antibiotics under the number INA 01267, was isolated and identified from a briquette of Fujian Chinese tea. The species identification was carried out based on morphocultural characteristics and DNA sequencing. This study is aimed at determining the feasibility of making postfermented herbal teas using E. cristatum and to evaluate their quality. Autofermented herbal teas from Chamaenerion angustifolium (fireweed) and Malus domestica (apple tree) served as the starting material for this study. The change in the concentration of phenolic compounds, organic acids, sugars, and free amino acids was observed for herbal teas subjected to postfermentation with E. cristatum INA 01267. It was found that the E. cristatum INA 01267 strain does not have antimicrobial activity and does not form mycotoxins, which is an indicator of food safety. [ABSTRACT FROM AUTHOR]

Experiments with the crossover superconductors between standard types I and II revealed exotic magnetic flux patterns where Meissner domains coexist with islands of the vortex lattice as well as with vortex clusters and chains. Until now a comprehensive theory for such configurations has not been presented. We solve this old-standing fundamental problem by developing an approach which combines the perturbation expansion of the microscopic theory with statistical simulations and which requires no prior assumption on the vortex distribution. Our study offers the most complete picture of the interchange of the superconductivity types available so far. The mixed state in this regime reveals a rich manifold of exotic configurations, which reproduce available experimental results. Our work introduces a pattern formation mechanism that originates from the self-duality of the theory that is universal and not sensitive to the microscopic details. Classification into type I and II reflects different responses of a superconductor to an applied magnetic field, however, there are intertype materials with unique properties and atypical vortex configurations. The authors study vortex patterns in this regime revealing that their properties are governed by a universal material independent mechanism, which amends the dual classification. [ABSTRACT FROM AUTHOR]

Abstract—Approaches to stabilizing the cells of lactic acid organisms (LAO) investigated in the present work resulted in maintaining the viable cell titer at 107–108 cells/mL, the value recommended for the LAO titer in foodstuffs, for 12 months. Natural LAO associations selected for long-term preservation of LAO cell viability exhibited high efficiency. Lactic acid bacteria Lactobacillus plantarum and yeasts Candida parapsilosis were isolated from the association isolated from marketed curdled milk and selected for 6 months. The death rate of these LAO in binary culture (50% of each component) was several times lower than in monocultures. Adding other approaches for cell stabilization in a binary LAO culture (anoxic conditions and stabilizing antioxidant and biopolymer supplements) resulted in a 5- to 6-fold increase in the number of viable cells after 12-month storage. The algorithm for combined application of several approaches to prolongation of cell viability in the cultures of lactic acid microorganisms during long-term storage (up to 12 months) was not reported previously. It may be recommended for LAO cell stabilization both in fermented milk products and in leaven cultures. This is the first report of C. parapsilosis as the yeast component of a stable association with lactic acid bacteria. [ABSTRACT FROM AUTHOR]

An Erratum to this paper has been published: https://doi.org/10.1134/S0021364024020012 [ABSTRACT FROM AUTHOR]

The preservation of activity of extracellular enzymes in soil is presently associated with their immobilization on organic or inorganic carriers. Enzyme immobilization results, however, in a significant decrease in enzymatic activity. In the present work, the mechanism responsible for promotion of the catalytic activity was revealed, as well as the favorable effect of low-molecular alkylhydrozybenzenes of the class of alkylresorcinols, which are common in soil organic matter, on stability of immobilized enzymes (exemplified by amylases) by their post-translational modification. Optimal conditions (enzyme to sorbent ratio, pH optimum, CaCl concentration, and sorption time) for amylase sorption on a biological sorbent (yeast cell walls) were determined and decreased activity of the immobilized enzyme compared to its dissolved state was confirmed. Alkylresorcinols (CAHB) at concentrations of 1.6 to 80 mM were found to cause an increase of amylase activity both in the case of already sorbed enzymes (by 30%) and in the case of a free dissolved enzyme with its subsequent immobilization (by 50-60%). In both cases, the optimal CAHB concentration was 16 mM. Amylase stability was determined for C7AHB-modified and unmodified enzymes immobilized on the biological sorbent after two cycles of freezing (-20°C) and thawing (4°C). Inverse dependence was revealed between increasing stability of CAHB-modified enzymes and an increase in their activity, as well as higher stability of immobilized modified amylases than of the dissolved modified enzyme. Investigation of the effect of CHOB-modification in the preservation of activity in immobilized amylases after four freeze-thaw cycles revealed: (1) better preservation of activity by the modified immobilized enzymes compared to immobilized ones; (2) differences in the dynamics of activity loss within compared pairs, with activity of immobilized amylases decreasing after the second cycle to a lower level (42%) than activity of the modified immobilized enzymes after the fourth cycle (48%). These results demonstrate that in the preservation of activity of extracellular enzymes in soil both stabilization mechanisms are of importance: immobilization on organic carriers and modification of the enzyme conformation by low-molecular compounds with the functions of chemical chaperones. [ABSTRACT FROM AUTHOR]

We investigate how the interplay of quantum confinement and level broadening caused by disorder affects superconducting correlations in ultra-small metallic grains. We use the electron-phonon interaction-induced electron mass renormalization and the reduced static-path approximation of the BCS formalism to calculate the critical temperature as a function of the grain size. We show how the strong electron-impurity scattering additionally smears the peak structure in the electronic density of states of a metallic grain and imposes additional limits on the critical temperature under strong quantum confinement. [ABSTRACT FROM AUTHOR]

The possibility of using nuclear explosions to prevent dangerous space objects, specifically, the asteroid Apophis, from colliding with our planet is evaluated. Two variants are considered: delivery of an impulse capable of deflecting the trajectory to a safe distance from Earth or fragmentation by means of a powerful explosion into fragments small enough not to cause a catastrophe during an encounter with Earth. The dynamics of the destruction of the asteroid is examined. The fragment size distribution after a nuclear explosion with a definite energy release is presented. It is concluded that to prevent a dangerous collision between our planet and the asteroid Apophis the nuclear explosions must be applied well ahead of time. [ABSTRACT FROM AUTHOR]

Recently fabricated single-crystalline atomically flat metallic nanofilms are in fact quantum-engineered multiband superconductors. Here the multiband structure is dictated by the nanofilm thickness through the size quantization of the electron motion perpendicular to the nanofilm. This opens the unique possibility to explore superconductivity in well-controlled multi-band systems. However, a serious obstacle is the absence of a convenient and manageable theoretical tool to access new physical phenomena in such quasi-two-dimensional systems, including interplay of quantum confinement and fluctuations. Here we cover this gap and construct the appropriate multiband Ginzburg-Landau functional for nano-thin superconductors. [ABSTRACT FROM AUTHOR]

The use of nuclear charges to prevent dangerous space objects from impacting the Earth is considered. Emphasis is placed on of two problems: imparting momentum to small cosmic bodies (SCBs) detected at a sufficient distance from the Earth to divert their trajectory to a safe distance from the planet; disintegration of SCBs by a nuclear explosion into fragments small enough compared to the initial body so that their impact on the Earth does not lead to an accident. The energy release of nuclear charges necessary to achieve this goal is estimated. The fragmentation process is considered using as an example a hypothetical SCB of the type of the asteroid Icarus. [ABSTRACT FROM AUTHOR]

We study the effect of electron confinement on the superconducting-to-normal phase transition driven by a magnetic field and/or on the current-carrying state of the superconducting condensate in nanowires. Our investigation is based on a self-consistent numerical solution of the Bogoliubov-de Gennes equations. We show that in a parallel magnetic field and/or in the presence of supercurrent the transition from superconducting to normal phase occurs as a cascade of discontinuous jumps in the superconducting order parameter for diameters D < 10 ÷ 15 nm at T = 0. The critical magnetic field exhibits quantum-size oscillations with pronounced resonant enhancements. [ABSTRACT FROM AUTHOR]

The adaptation of lactic acid bacteria (LAB) to unfavorable growth conditions, e.g., depletion of nutrient sources, overthreshold cell density of a population, or antibiotic impact, was shown to include: (1) formation of cyst-like dormant cells (CDC) providing for survival and species preservation and (2) realization of intra-population phenotypic variability, which is demonstrated by development of non-dominant colonies on plates inoculated with CDC suspensions. In Lactobacillus plantarum, the dormant cells, which retained viability and heat resistance for a long time, were formed in 10- and 20-fold concentrated suspensions of the stationary phase cells. In 4-month cell suspensions, two types of cells were present, CDC and L-forms. The CDC of Lactococcus lactis were formed in (1) post-stationary cultures grown under glucose limitation and (2) in stationary phase cultures resuspended in starvation medium (without glucose). Populations of CDC stored for different periods of time varied in the ability for phase variation; as a result, both variants exhibited a shift of the population’s CDC spectrum to the transition of the dominant S-colony type to the R-type up to complete substitution (by day 25). In Lactobacillus acidophilus AT-41, CDC appeared in (1) post-stationary cultures grown on a nitrogen-limited medium; (2) autolyzing cultures treated with ampicillin or erythromycin; and (3) concentrated (10- and 20-fold) suspensions of stationary-phase cells. At plating of L. acidophilus CDC, the substitution of the S-type for the dominant R-type in variants (1) (day 30), (2) (100 μg/ml ampicillin, day 10), and (3) (day 25) was 68.6%, 30.1%, and 61.2%, respectively. The S-variant of L. acidophilus was used for development of a novel lactofermented product based on vegetable (beet) juice fermentation, which sustained high titer of viable cells (2 × 106 cells/ml). [ABSTRACT FROM AUTHOR]

The effect of alkylhydroxybenzenes (AHBs) belonging to the class of alkylresorcinols differing in the degree of hydrophobicity—C7-AHB and more hydrophobic C12-AHB—on the resistance of Saccharomyces cerevisiae cells to heat shock and oxidative stress of lethal intensity was studied. Depending on structure and concentration, AHB added 2 h before exposure to stress had either an antistress or stress-potentiating effect on yeast cells in the mid-logarithmic growth phase. C7-AHB at concentrations 0.25–0.5 g/l caused a two-to fivefold increase in the resistance of yeast cells to hydrogen peroxide (30–150 mM), whereas C12-AHB reduced it at all concentrations. C7-AHB and C12-AHB had a similar effect on yeast subjected to heat shock (45°C, 30 min). It was found that the degree of the protective effect of C7-AHB and potentiating effect of C12-AHB depended on the nature of the stressor, being more pronounced in heat shock. The environmental significance of the antistress and stress-potentiating effects of microbial AHBs is discussed. [ABSTRACT FROM AUTHOR]

The properties of a clean superconductor with nanoscale dimensions are governed by quantum confinement of the electrons. This results in a spatially inhomogeneous superconducting condensate and in the formation of new Andreev-type quasiparticle states. These states are mainly located beyond regions where the superconducting condensate is enhanced. A numerical self-consistent solution of the Bogoliubov-de Gennes equations for a cylindrical metallic nanowire shows that these new Andreev-type states decrease the ratio of the energy gap to the critical temperature. [ABSTRACT FROM AUTHOR]

Kinetic characteristics of model enzymes and physicochemical properties of globular proteins modified by chemical analogues of low-molecular-weight microbial autoregulators (alkylhydroxybenzenes, AHBs) have been studied. C7 and C12 AHB homologues were used, differing in the length of the alkyl radical and the capacity for weak physicochemical interactions. Both homologues affected the degree of protein swelling, viscosity, and the degree of hydrophobicity. The effects depended on the structure of AHBs, their concentration, and pH of the solution, which likely reflects changes in the charge of the protein globule and its solvate cover. Variations of hydrophobicity indices of AHB-modified enzymes (trypsin and lysozyme) were coupled to changes in the catalytic activity. The values of K M, measured for the enzymes within both AHB complexes, did not change, whereas V max increased (in the case of C7 complexes) or decreased (C12 complexes). Possible molecular mechanisms of changes in the physicochemical and catalytic parameters of enzymatically active proteins, induced by modification with structurally distinct AHBs, are described, with emphasis on targeted regulation of functional activity. [ABSTRACT FROM AUTHOR]

It has been shown that one of the alkyl hydroxybenzenes, C7-AHB, can be used in malting for regulating barley growth. Depending on concentration (0.01–1.0%) and duration (from 10 min to 6 h), treatment of barley with a C7-AHB solution stimulates embryo development (0.01–0.02%) or suppresses the growth of vegetative organs (>0.5%) and modulates enzyme activities in germinating grains. Stimulation of the activities of the amylolytic and protein–proteinase complexes in barley depending on the C7-AHB concentration improves malt quality by increasing both the degree of its saccharification and protein dissolution. [ABSTRACT FROM AUTHOR]

The purpose of the present article is to call attention to some realistic quasiparticle-based description of quark/gluon matter and its consistent implementation in thermodynamics. A simple and transparent representation of the thermodynamic consistency conditions is given. This representation allows one to review critically and systemize available phenomenological approaches to the deconfinement problem with respect to their thermodynamic consistency. Particular attention is paid to the development of a method for treating the string screening in the dense matter of unbound color charges. The proposed method yields an integrable effective pair potential that can be incorporated into the mean-field picture. The results of its application are in reasonable agreement with lattice data on the QCD thermodynamics. [ABSTRACT FROM AUTHOR]

The modified Bogoliubov model where the primordial interaction is replaced by the t matrix is reinvestigated. It is shown to provide a negative value of the kinetic energy for a strongly interacting dilute Bose gas, contrary to the original Bogoliubov model. To clear up the origin of this failure, the correct values of the kinetic and interaction energies of a dilute Bose gas are calculated. It is demonstrated that both the problem of the negative kinetic energy and the ultraviolet divergence, dating back to the well-known paper of Lee, Yang and Huang, is connected with an inadequate picture of the short-range boson correlations. These correlations are reconsidered within the thermodynamically consistent model proposed earlier by the present authors. Found results are in absolute agreement with the data of the Monte-Carlo calculations for the hard-sphere Bose gas. [ABSTRACT FROM AUTHOR]

The QCD phase transition is treated within a statistical model taking into account the coexistence of interacting quark-gluon and hadron phases. Being in agreement with the recent lattice QCD data, this statistical mixed phase model predicts that the 'softest point' of the equation of state, resulting in the longest-lived fireball effect, is at ε GeV/fm. It is shown that this 'softest point' is washed out at the baryon densities higher than the normal nuclear density. The approach is extended to include strangeness. Attention is drawn to the study of signatures for forming the mixed quark-hadron phase of nuclear matter in the collision energy range E ≈ 2-10 GeV/A. [ABSTRACT FROM AUTHOR]

A statistical model of deconfinement is constructed by treating hadrons as clusters of elementary objects, gluons and quarks. The basis of the model is an effective cluster Hamiltonian. The principle of thermodynamic equivalence for Hamiltonians is formulated, which makes it possible to describe all the thermodynamics of the system with an effective Hamiltonian in a completely correct way. This principle yields restrictions, called the conditions of thermodynamic correctness, controlling the choice of the cluster Hamiltonians. The clustering, at low temperature and density, of partons into hadrons means confinement while the inverse process of the cluster disintegration corresponds to deconfinement. To check the accuracy of the model, detailed calculations for the region of zero baryon density have been made for which computer simulations on the lattice are known. Our results are found to be in nice agreement with the lattice numerical data. [ABSTRACT FROM AUTHOR]

A new approach is advanced for treating quark systems. The approach considers all possible quark states: unbound (quasi-free) quarks and strongly bound (confined) n-quark hadron clusters with arbitrary n, satisfying selection rules. All admissible reactions of decay and fusion among multiquarks and between the latter and quasi-free quarks are taken into account. The behaviour of the quark-hadron matter on the temperature-density plane is studied. The deconfinement of quarks is found to be rather a continuous process than an abrupt transition. [ABSTRACT FROM AUTHOR]

Quantum confinement is known to affect a nanosized superconductor through quantum‐size variations of the electronic density of states. Here, it is demonstrate that there is another quantum‐confinement mechanism overlooked in previous studies. In particular, it is found that the electron–electron attraction can be enhanced due to quantum‐confinement modifications of electronic wave functions. The superconducting correlations are strengthened by such quantum mechanical effect, which creates a subtle interplay with surface–substrate phonon modifications. The combined effect depends on nanofilm thickness and can be controlled by nanoarchitechture. The calculations are in a reasonable agreement with experiments performed on high‐quality aluminum films. These findings shed light on the long‐standing problem of the size dependence of the critical temperature in low‐dimensional superconductors. Nanostructured superconductors attract significant interest because their properties may strongly vary with the system geometry and dimensions. This opens prospects of architecting superconducting nanodevices in order to tune their characteristics. Here the authors demonstrate that one of promising examples is high‐quality metallic nanofilms, where superconductivity is enhanced by quantum‐size effects and the enhancement is well controlled by the nanofilm thickness. [ABSTRACT FROM AUTHOR]

Conventional superconductivity is inevitably suppressed in ultra-small metallic grains for characteristic sizes smaller than the Anderson limit. Experiments have shown that above the Anderson limit the critical temperature may be either enhanced or reduced when decreasing the particle size, depending on the superconducting material. In addition, there is experimental evidence that whether an enhancement or a reduction is found depends on the strength of the electron-phonon interaction in the bulk. We reveal how the strength of the e-ph interaction interplays with the quantum-size effect and theoretically obtain the critical temperature of the superconducting nanograins in excellent agreement with experimental data. We demonstrate that strong e-ph scattering smears the peak structure in the electronic density-of-states of a metallic grain and enhances the electron mass, and thereby limits the highest Tc achievable by quantum confinement. [ABSTRACT FROM AUTHOR]

Superconductors, ideally diamagnetic when in the Meissner state, can also exhibit paramagnetic behavior due to trapped magnetic flux. In the absence of pinning such paramagnetic response is weak, and ceases with increasing sample thickness. Here we show that in multiband superconductors paramagnetic response can be observed even in slab geometries, and can be far larger than any previous estimate - even multiply larger than the diamagnetic Meissner response for the same applied magnetic field. We link the appearance of this giant paramagnetic response to the broad crossover between conventional Type-I and Type-II superconductors, where Abrikosov vortices interact non-monotonically and multibody effects become important, causing unique flux configurations and their locking in the presence of surfaces. [ABSTRACT FROM AUTHOR]

Recent progress in materials synthesis enabled fabrication of superconducting atomically flat single-crystalline metallic nanofilms with thicknesses down to a few monolayers. Interest in such nano-thin systems is attracted by the dimensional 3D–2D crossover in their coherent properties which occurs with decreasing the film thickness. The first fundamental aspect of this crossover is dictated by the Mermin–Wagner–Hohenberg theorem and concerns frustration of the long-range order due to superconductive fluctuations and the possibility to track its impact with an unprecedented level of control. The second important aspect is related to the Fabri–Pérot modes of the electronic motion strongly bound in the direction perpendicular to the nanofilm. The formation of such modes results in a pronounced multiband structure that changes with the nanofilm thickness and affects both the mean-field behavior and superconductive fluctuations. Though the subject is very rich in physics, it is scarcely investigated to date. The main obstacle is that there are no manageable models to study a complex magnetic response in this case. Full microscopic consideration is rather time consuming, if practicable at all, while the standard Ginzburg–Landau theory is not applicable. In the present work we review the main achievements in the subject to date, and construct and justify an efficient multiband mean-field formalism which allows for numerical and even analytical treatment of nano-thin superconductors in applied magnetic fields. [ABSTRACT FROM AUTHOR]