Tuning the Multiferroic Properties of BiFeO_{3} under Uniaxial Strain.

More than twenty years ago, multiferroic compounds combining in particular magnetism and ferroelectricity were rediscovered. Since then, BiFeO_{3} has emerged as the most outstanding multiferroic by combining at room temperature almost all the fundamental or applicative properties that may be desired: electroactive spin wave excitations called electromagnons, conductive domain walls, or a low band gap of interest for magnonic devices. All these properties have so far only been discontinuously strain engineered in thin films according to the lattice parameter imposed by the substrate. Here we explore the ferroelectricity and the dynamic magnetic response of BiFeO_{3} bulk under continuously tunable uniaxial strain. Using elasto-Raman spectroscopy, we show that the ferroelectric soft mode is strongly enhanced under tensile strain and driven by the volume preserving deformation at low strain. The magnonic response is entirely modified with low energy magnon modes being suppressed for tensile strain above pointing out a transition from a cycloid to an homogeneous magnetic state. Effective Hamiltonian calculations show that the ferroelectric and the antiferrodistortive modes compete in the tensile regime. In addition, the homogeneous antiferromagnetic state becomes more stable compared to the cycloidal state above a +2% tensile strain close to the experimental value. Finally, we reveal the ferroelectric and magnetic orders of BiFeO_{3} under uniaxial strain and how the tensile strain allows us to unlock and to modify in a differentiated way the polarization and the magnetic structure.

[Efficiency of the attention networks and severity of positive and negative symptoms in schizophrenia]. / Effektivnost' setei vnimaniya i vyrazhennost' pozitivnoi i negativnoi simptomatiki pri shizofrenii.

OBJECTIVE: To examine the characteristics of the event related potentials during the attention network test in patients with schizophrenia depending on the severity of positive and negative symptoms. MATERIAL AND METHODS: The study included 20 patients with schizophrenia, 10 of them with a predominance of positive symptoms and 10 patients with a predominance of negative symptoms. All patients were diagnosed with paranoid schizophrenia (F20.0). Attention function was assessed using the attention network test with parallel recording of evoked responses. Differences in the amplitude and latency of N100 potential when presented with different types of cues, as well as P300 potential when identifying a congruent and incongruent flanker were analyzed. RESULTS: A comparative analysis of N100 potential for neutral cues and flankers showed significantly lower amplitude and longer latency in the group of patients with a predominance of negative symptoms (Cz channel).The amplitude of the evoked N100 response upon presentation of central and spatial cues was significantly higher in the group of patients with a predominance of positive symptoms. An analysis of P300 potential in Fz channel with congruent and incongruent flankers revealed no differences in the amplitude of both stimuli in the group of patients with a predominance of negative symptoms, while the amplitude of the evoked response to congruent and incongruent flankers was significantly higher in the group with a predominance of positive symptoms. In the group of patients with a predominance of positive symptoms, an inverse flanker response was established - P300 amplitude was significantly higher upon presentation of an incongruent flanker. CONCLUSION: The specific characteristics of evoked responses describing the features of such systems of attention as vigilance, orientation and conflict resolution have been established.

COVID-19 in Russia: Clinical and Immunological Features of the First-Wave Patients.

The coronavirus disease outbreak in 2019 (COVID-19) has now achieved the level of a global pandemic and affected more than 100 million people on all five continents and caused over 2 million deaths. Russia is, needless to say, among the countries affected by SARS-CoV-2, and its health authorities have mobilized significant efforts and resources to fight the disease. The paper presents the result of a functional analysis of 155 patients in the Moscow Region who were examined at the Central Clinical Hospital of the Russian Academy of Sciences during the first wave of the pandemic (February-July, 2020). The inclusion criteria were a positive PCR test and typical, computed tomographic findings of viral pneumonia in the form of ground-glass opacities. A clinical correlation analysis was performed in four groups of patients: (1) those who were not on mechanical ventilation, (2) those who were on mechanical ventilation, and (3) those who subsequently recovered or (4) died. The correlation analysis also considered confounding comorbidities (diabetes, metabolic syndrome, hypertension, etc.). The immunological status of the patients was examined (levels of immunoglobulins of the M, A, G classes and their subclasses, as well as the total immunoglobulin level) using an original SARS-CoV-2 antibody ELISA kit. The ELISA kit was developed using linear S-protein RBD-SD1 and NTD fragments, as well as the N-protein, as antigens. These antigens were produced in the prokaryotic E. coli system. Recombinant RBD produced in the eukaryotic CHO system (RBD CHO) was used as an antigen representing conformational RBD epitopes. The immunoglobulin A level was found to be the earliest serological criterion for the development of a SARS-CoV-2 infection and it yielded the best sensitivity and diagnostic significance of ELISA compared to that of class M immunoglobulin. We demonstrated that the seroconversion rate of "early" N-protein-specific IgM and IgA antibodies is comparable to that of antibodies specific to RBD conformational epitopes. At the same time, seroconversion of SARS-CoV-2 N-protein-specific class G immunoglobulins was significantly faster compared to that of other specific antibodies. Our findings suggest that the strong immunogenicity of the RBD fragment is for the most part associated with its conformational epitopes, while the linear RBD and NTD epitopes have the least immunogenicity. An analysis of the occurrence rate of SARS-CoV-2-specific immunoglobulins of different classes revealed that RBD- and N-specific antibodies should be evaluated in parallel to improve the sensitivity of ELISA. An analysis of the immunoglobulin subclass distribution in sera of seropositive patients revealed uniform induction of N-protein-specific IgG subclasses G1-G4 and IgA subclasses A1-A2 in groups of patients with varying severity of COVID-19. In the case of the S-protein, G1, G3, and A1 were the main subclasses of antibodies involved in the immune response.

[Obstructive sleep apnea syndrome and cognitive impairment]. / Cindrom obstruktivnogo apnoé sna i kognitivnye narusheniia.

Sleep-disordered breathing is associated with sleep fragmentation and reduced blood oxygenation due to apnea and hypopnea episodes. Multiple studies indicate that obstructive sleep apnea syndrome (OSAS) can have negative impact on cognitive functioning, primarily executive functions, attention, and episodic memory. The attention is also focused on cognition in patients with neurologic and psychiatric comorbidities. There are different explanatory models, which show the mechanisms of OSAS influence on cognition. However, it is still unclear how the initial severity of the disease and clinical outcomes interrelate, and which factors play role in the compensation of cognitive dysfunction. Better understanding of these issues is crucial for the prevention of cognitive impairment and rehabilitation of cognitive functioning.

[Characteristics of thinking recorded in experimental psychological studies of young people]. / Osobennosti myshleniia u molodykh liudei, fiksiruemye v éksperimental'nykh psikhologicheskikh issledovaniiakh.

AIM: To identify the features of thinking of young people, whose mental development was carried out in conditions of life virtualization (in a networked society). MATERIAL AND METHODS: The study included 310 mentally healthy respondents, aged from 18 to 20 years, who study in universities of St. Petersburg. Classical pathopsychological methods 'Exclusion of excess' and 'Comparison of concepts' were administered. The answers were divided into normative and non-normative, the latter were designated as psychopathological thinking phenomena (PPTP). RESULTS AND CONCLUSION: PPTP were identified in 84.3% of the answers, with the frequency from 1 to 4 and more. The significant prevalence of PPTP in healthy young people was shown. PPTP in young people were unpredictable and chaotic. They were represented by generalizations based on latent signs, broad generalizations, and by a number of parameters characteristic of distortion of thinking. These features should not be considered as specific indicators of thinking disorders because they reflect only changed conditions of mental development characterized by the deformation of semantic matrices and substitution of hierarchic structures for network structures and excess of signs with multiple meanings. The results should be taken into consideration when evaluating the results of pathopsychological experiments.

Magneto-optical properties of Au upon the injection of hot spin-polarized electrons across Fe/Au(0 0 1) interfaces.

We demonstrate a novel method for the excitation of sizable magneto-optical effects in Au by means of the laser-induced injection of hot spin-polarized electrons in Au/Fe/MgO(0 0 1) heterostructures. It is based on the energy- and spin-dependent electron transmittance of Fe/Au interface which acts as a spin filter for non-thermalized electrons optically excited in Fe. We show that after crossing the interface, majority electrons propagate through the Au layer with the velocity on the order of 1 nm fs-1 (close to the Fermi velocity) and the decay length on the order of 100 nm. Featuring ultrafast functionality and requiring no strong external magnetic fields, spin injection results in a distinct magneto-optical response of Au. We develop a formalism based on the phase of the transient complex MOKE response and demonstrate its robustness in a plethora of experimental and theoretical MOKE studies on Au, including our ab initio calculations. Our work introduces a flexible tool to manipulate magneto-optical properties of metals on the femtosecond timescale that holds high potential for active magneto-photonics, plasmonics, and spintronics.

[Stress levels and coping behavior in patients with chronic insomnia]. / Uroven' stressa i stress-preodolevaiushchee povedenie u patsientov s khronicheskoi insomniei.

AIM: To assess stress level and coping strategies in chronic insomnia as its potential psychological factors. MATERIAL AND METHODS: The study group included 29 patients (19 women), aged 18-55 years old (mean age 33.1±2.1 years), with chronic insomnia diagnosed in accordance with the International Classification of Sleep Disorders III. The control group was formed by 32 subjects (11 men), aged 18-55 years old (mean age 31.5±2.0 years), without sleep disorders. Insomnia Severity Index and polysomnography were used to evaluate sleep quality. Stress level and coping strategies were assessed via an interview (stressfull life events during last year, their duration, their controllability, unexpectedness, and outcome), and by 'Level of subjective control' and 'Ways of coping questionnaires'. RESULTS: Both groups were comparable by the mean number of significant events during last year (4.97±0.34 vs 4.72±0.23, p=0.54). Patients with insomnia more often reported the loss of a relative (p=0.04), while controls more frequently reported positive events, such as pregnancy (p=0.007) or wedding (p=0.02) among close ones. Insomniacs more often described the stressful events as uncontrolled (p<0.001) and prolonged (p<0.001). They demonstrated lower indices of all the scales of the 'Level of subjective control', questionnaire except the scale of interpersonal attitudes. They rarely implemented confrontive coping (p=0.001), seeking social support (p<0.001), accepting responsibility (p<0.001) and positive reappraisal (p<0.001). CONCLUSIONS: The interpretation of stressful events and personal response in insomnia patients might be considered as psychological risk factors for insomnia development.

Analysis of the time-resolved magneto-optical Kerr effect for ultrafast magnetization dynamics in ferromagnetic thin films.

We discuss fundamental aspects of laser-induced ultrafast demagnetization probed by the time-resolved magneto-optical Kerr effect (MOKE). Studying thin Fe films on MgO substrate in the absence of electronic transport, we demonstrate how to disentangle pump-induced variations of magnetization and magneto-optical coefficients. We provide a mathematical formalism for retrieving genuine laser-induced magnetization dynamics and discuss its applicability in real experimental situations. We further stress the importance of temporal resolution achieved in the experiments and argue that measurements of both time-resolved MOKE rotation and ellipticity are needed for the correct assessment of magnetization dynamics on sub-picosecond timescales. The framework developed here sheds light onto the details of the time-resolved MOKE technique and contributes to the understanding of the interplay between ultrafast laser-induced optical and magnetic effects.

Comparative Culturing of 3T3 Swiss J2 Mouse Embryo Fibroblasts on Modified Chitosan Matrices.

Comparative culturing of mouse embryo fibroblasts on chitosan matrices and culture plastic was carried out. During the first 2 h of culturing (lag phase), cell adhesion to chitosan and chitosan-gelatin matrices was 20-30% higher than adhesion to culture plastic (control). During the stationary phase, 80% cells adhered to chitosan matrices (vs. 60% in the control). Cell culturing on chitosan matrices was carried out without medium replacement with fresh portions. The cells remained viable within 5 days of culturing. Cell death phase was observed on day 6 of culturing on chitosan matrices: cell adhesion dropped to 50%. Culturing on culture plastic was carried out with daily medium replacement with a fresh portion. Cell death phase (50% decrease in the number of adherent cell) under these condition was observed on day 5. It seems that the observed effect was a result of contact interactions of cell integrins and chitosan ligands, modulation of transmembrane signal, eventually modifying the expression of cell genes. This effect can be required in regenerative medicine for production of primary cell culture.

[Intraperitoneal and retromuscular abdominal wall repair using ultra-light and titanium-containing polypropylene mesh (experimental research)]. / Intraperitoneal'naya i retromuskulyarnaya plastika bryushnoi stenki ul'tralegkimi polipropilenovymi i titansoderzhashchimi endoprotezami (eksperimental'noe issledovanie).

AIM: To study experimental possibility of light, ultra-light and titanium-containing endoprostheses implantation for postoperative hernias correction. MATERIAL AND METHODS: Abdominal wall repair was simulated in 72 rabbits. In the first group polypropylene mesh with fibers diameter of 90 microns and surface density of 36 g/m2 was used. In the second group we applied polypropylene mesh with fibers diameter of 65 microns and thin layer of titanium. Their surface density was 16 g/m2. Intraperitoneal onlay mesh (IPOM) and sublay retromuscular (SRM) techniques were used in group 1 and 2 respectively. Animals were taken out from the experiment in 30 and 60 days. Adhesive process in implantation area was evaluated using the method of Egiev V.N. and Lyadov V.K. RESULTS: The most pronounced adhesive process was observed in IPOM series. Type of endoprosthesis and terms of postoperative period did not significant effect adhesive process. SRM method was associated with significantly less pronounced adhesions. Analysis of all data showed that severity of adhesive process was significantly higher in IPOM series compared with SRM technique. CONCLUSION: Our study showed that severity of abdominal adhesive process associated with repair using ultra-light mesh is completely determined by surgical technique and did not depend on type of endoprosthesis and terms of postoperative period. Described implants should be used for retromuscular implantation rather intraperitoneal position.

[INFLUENCE OF TITANIUM COATING ON THE BIOCOMPATIBILITY OF POLYPROPYLENE IMPLANTS].

Comparative analysis of the proliferative activity of inflammatory cells and distribution of collagen types I and III was carried out around the net materials of polypropylene and titanium coating polypropylene using im- munohistochemical method and polarization microscopy. Experimental modeling of implanted mesh material were made in the soft tissues of the lumbar region of rats. On the 7th postoperative day, quantitative analysis of proliferating cells delected using antibodies to the Ki-67 protein showed, a significant decrease (p < 0.001) in the number of proliferating cells around the network elements of the polypropylene (29.1 ± 5.7 %), when com- pared to similar figures of infiltrates in titanium coating polypropylene (33.6 ± 3.1 %). Similar patterns were found on the 30th day of the experiment--15.9 ± 4.3 and 26.9 ± 3.6%--respectively (p < 0.001). Different types of collagen fibers in the granulomas around various types of implanted mesh material were detected on sections stained with Sirius red at polarizing light. On the 7th day after surgery, the ratio of collagen fibers ty- pe I and III in granulomas around the mesh material made of polypropylene was 1.085 ± 0.022 and this rati around materials of titanium coated polypropylene was higher--1.107 ± 0.013 (p = 0.017). On the 30th posto- perative day in the interface area ratio I/III collagen significantly increased and amounted to 1.174 ± 0.036 and 1.246 ± 0.102, respectively (p = 0.045). Assessing the impact of the use of titanium as a coating on the po- lypropylene, it can be argued that it promotes the formation of collagen I type and a more mature connective tis- sue around the mesh of the implants.

[Application of heated oxygen-helium mixture for combined treatment of community-acquired pneumonia].

Community-acquired pneumonia (CAP) is the commonest infectious disease characterized by the high lethality rate. The aim of this work was to estimate the efficacy of introducing inhalation of heated oxygen-helium mixture (thermoheliox) into standard therapy of CAP. The study included 50 patients with moderately severe CAP 25 patients of group 1 were given standard therapy plus thermoheliox, those of group 2 were treated by standard method. Group 1 showed faster disappearance of symptoms and physical signs including inflammatory changes (chemiluminescence of whole blood) and cardiac rhythm variability as well as more complete recovery of pneumonia upon X-ray examination. It is concluded that thermoheliox is an effective agent for pathogenetic therapy of community-acquired pneumonia.

[Fungal spores: dormancy, germination, chemical composition, and role in biotechnology (review)].

This review is focused on one of the stages of ontogenesis distinctive by its particular tolerance to the action of unfavorable factors and ability to retain the genomic material for a long period of time, i.e., fungal spores. The major part is devoted to the characterization of the specific stage typical for spores, which is called dormancy. Data are presented characterizing the carbohydrate and lipid composition of spores, with special attention being paid to the role of carbohydrate protectors, in particular, trehalose and mannite, as well as to the role of rafts in the process of sporogenesis. The role of special compounds called autoinhibitors and autostimulators in the process of exit from dormancy is discussed. The final section deals with the role of spore seeding material in biotechnological processes. Data on the correlation between the chemical composition of spores, their ability to remain dormant, and the germination process are considered. Special biotechnological approaches are presented for the first; they allow for the preservation of the germinating ability of spores, intensification of sporogenesis, changes in the ratio of final fermentation products, and an increase in their yield.

[The optimal treatment algorithm of radial nerve injuries].

The results of rehabilitation of 52 patients with radial nerve injuries were comparatively analyzed: the traditional rehabilitation complex (massage, training, etc.) was compared with the method of functional biomanagement. The technical characteristics of the designed functional cast were thoroughly described. The study demonstrated that reinnervation and functional recovery of the denervated muscles without segmental influence were significantly slower.

[Early motor rehabilitation with the help of a software/hardware complex "Vertical" in acute period of stroke].

The purpose of our study was the investigation of effectiveness of restoration of lost motor functions in acute period of stroke with the help of software/hardware complex "Vertical". This complex includes a functional bed-trainer for leg movements with phase-dependent functional electrical myostimulation (FES). Fifty-five subjects (mean age 64 +/-1.5 years) were assigned randomly to two groups receiving standard rehabilitation (a control group--27 subjects) and standard rehabilitation combined with the treatment by the "Vertical" complex (FES group--28 subjects). The treatment course was started on average 9 +/- 4 days after stroke and consisted of 30 min sessions 5 days per week during 2 weeks. Outcome was assessed by a battery of scales, everyday movement abilities and biomechanical parameters before and after treatment. No significant differences were found in baseline measurements. After the treatment, there was a positive dynamics in both groups with significant improvement in scores in the FES group. Most of patients of this group (67%) had hemiparesis of mild degree compared to the control group (7%, p < 0.05) to the end of treatment. Also 89% of subjects in the FES group were able to walk without assistance after treatment as compared to the control group (p < 0.05). There was a significant improvement in ankle flexors and extensors force of the paretic leg as well as in ankle joint movements of voluntary "walking" in the supine position in the FES group (p < 0.05).

[Antitumor effect of low-intensity extremely high-frequency electromagnetic radiation on a model of solid Ehrlich carcinoma].

The influence of different exposure regimes of low-intensity extremely high-frequency electromagnetic radiation on the growth rate of solid Ehrlich carcinoma in mice has been studied. It was shown that, at an optimum repetition factor of exposure (20 min daily for five consecutive days after the tumor inoculation), there is a clearly pronounced frequency dependence of the antitumor effect. The analysis of experimental data indicates that the mechanisms of antitumor effects of the radiation may be related to the modification of the immune status of the organism. The results obtained show that extremely high-frequency electromagnetic radiation at a proper selection of exposure regimes can result in distinct and stable antitumor effects.

[Analysis of the possible involvement of the glutamate transporter gene EAAT2 and the glutamate receptor genes GRIA1 and GRIA2 in pathogenesis of motor neuron disease in the Russian population].

Polymorphisms of the genes of the glutamatergic system EAAT2, GRIA1, and GRIA2 have been analyzed in patients with sporadic motor neuron disease (MND) from Russia. The disease is not associated with polymorphic alleles of the genes studied, which indicates that EAAT2, GRIA1, and GRIA2 play an insignificant role in the pathogenesis of sporadic MND.