The “Angiogenic Switch” and Functional Resources in Cyclic Sports Athletes

Regular physical activity in cyclic sports can influence the so-called “angiogenic switch”, which is considered as an imbalance between proangiogenic and anti-angiogenic molecules. Disruption of the synthesis of angiogenic molecules can be caused by local changes in tissues under the influence of excessive physical exertion and its consequences, such as chronic oxidative stress and associated hypoxia, metabolic acidosis, sports injuries, etc. A review of publications on signaling pathways that activate and inhibit angiogenesis in skeletal muscles, myocardium, lung, and nervous tissue under the influence of intense physical activity in cyclic sports. Materials: We searched PubMed, SCOPUS, Web of Science, Google Scholar, Clinical keys, and e-LIBRARY databases for full-text articles published from 2000 to 2020, using keywords and their combinations. Results: An important aspect of adaptation to training loads in cyclic sports is an increase in the number of capillaries in muscle fibers, which improves the metabolism of skeletal muscles and myocardium, as well as nervous and lung tissue. Recent studies have shown that myocardial endothelial cells not only respond to hemodynamic forces and paracrine signals from neighboring cells, but also take an active part in heart remodeling processes, stimulating the growth and contractility of cardiomyocytes or the production of extracellular matrix proteins in myofibroblasts. As myocardial vascularization plays a central role in the transition from adaptive heart hypertrophy to heart failure, further study of the signaling mechanisms involved in the regulation of angiogenesis in the myocardium is important in sports practice. The study of the “angiogenic switch” problem in the cerebrovascular and cardiovascular systems allows us to claim that the formation of new vessels is mediated by a complex interaction of all growth factors. Although the lungs are one of the limiting systems of the body in cyclic sports, their response to high-intensity loads and other environmental stresses is often overlooked. Airway epithelial cells are the predominant source of several growth factors throughout lung organogenesis and appear to be critical for normal alveolarization, rapid alveolar proliferation, and normal vascular development. There are many controversial questions about the role of growth factors in the physiology and pathology of the lungs. The presented review has demonstrated that when doing sports, it is necessary to give a careful consideration to the possible positive and negative effects of growth factors on muscles, myocardium, lung tissue, and brain. Primarily, the “angiogenic switch” is important in aerobic sports (long distance running). Conclusions: Angiogenesis is a physiological process of the formation of new blood capillaries, which play an important role in the functioning of skeletal muscles, myocardium, lung, and nervous tissue in athletes. Violation of the “angiogenic switch” as a balance between proangiogenic and anti-angiogenic molecules can lead to a decrease in the functional resources of the nervous, musculoskeletal, cardiovascular, and respiratory systems in athletes and, as a consequence, to a decrease in sports performance.     

Gold supported on ceria and ceria–alumina promoted by molybdena for complete benzene oxidation

New gold–molybdena catalysts supported on ceria and ceria–alumina in reaction of complete benzene oxidation were studied. The catalysts were characterized by means of XRD, TPR, XPS and Raman spectroscopy. High and stable catalytic activity was established in the temperature region 200–240 °C. The presence of gold causes a modification in ceria structure leading to an increase of Ce³⁺ and oxygen vacancies formation. The loading of Al³⁺ increases additionally the oxygen vacancies, while a tendency of decrease of Ce³⁺ amount was observed. The presence of alumina results also in a larger share of active oxygen species proved by analysis of O 1s XPS spectra. The differences in the activities within the starting temperature range (150–180 °C) and in the region of 100% conversion (200–240 °C) could be explained by supposing that in the LT region the electron transfer between nanosized gold and ceria particles via oxygen vacancies has a crucial role. In the HT region the oxygen mobility, provoked by the defective structure of ceria due to the presence of Al³⁺, becomes of prevailing importance. It was also concluded that alumina prevents the gold and ceria agglomeration, which is the main factor to avoid deactivation under extreme reaction conditions.     

Some features of spinning cuprammonium fibres into precipitation baths containing calcium salts

Conclusions On the basis of data on precipitating power and the rate of dehydration of cuprammonium solutions of cellulose, the fundamental possibility has been demonstrated of spinning fibres from such solutions into precipitation baths containing calcium salts, using the technological scheme for viscose fibre manufacture.The dependence of the basic characteristics of the freshly-spun fibre on calcium salt content and temperature of the precipitation bath has been found.Moscow Textile Institute. Translated from Khimicheskie Volokna, No. 1, pp. 11–13, January–February, 1987.     

Influence of pitch composition and surface properties of petroleum coke on their interaction during the preparation of carbon/carbon composites

The influence of pitch composition and surface properties of petroleum coke on the interaction of pitch and coke in the composite is studied. The adsorption results and EPR data indicate that recombination of paramagnetic centers and interaction of oxygen functional groups occur during the preparation of the composite. As a result of interaction between petroleum coke and pitch, polar compounds are concentrated in the adsorption layer. The baking criterion is used for the characterization of the baking ability of the pitches obtained as a result of different oxidation treatments of commercial coal tar pitch. It is determined that physico-chemical properties of the obtained pitches influence the value of the “baking criterion”. The kind of thermo-oxidation treatment of the parent pitch should be chosen hence achieving the maximum value of the baking criterion. For this purpose, the maximal part of the pitch has to take part in the adsorption layer.     

Location-based services deployment and demand: a roadmap model

The advancements in mobile, wireless and positioning technologies have enabled applications and services such as route guiding and emergency call-out assistance. These and other similar services have become known as ‘location-based services’ (LBS). The literature on LBS development and deployment addresses technological issues (for example, usability and integration) and issues related to LBS implementation—including LBS business models, adoption and customer concerns and requirements. In the study presented here LBS development and deployment were investigated from a case study perspective and the LBS landscape is explored and analyzed. The study finds that while the regulatory environment has played a critical role as a success factor in the markets investigated some of innovative business approaches may have been equally important as customer demand generators. Economies on the road to deploying LBS should therefore focus on creating a supportive environment encouraging the development of services, which meet the identified needs and requirements of the target customer market.     

Kinetics of redox processes in manganese oxides

The redox processes in ceramic and powder samples of α-Mn₂O₃ (kurnakite) and β-Mn₃O₄ (hausmannite) have been studied in the temperature range 20–1000°C. The results demonstrate that the conversion of α-Mn₂O₃ to β-Mn₃O₄ in the binary system Mn-O is essentially irreversible, even if there are nucleation centers in the form of the higher oxide α-Mn₂O₃ during the oxidation of hausmannite. It is shown that the high reactivity of hausmannite ground in a WC mill is not due to a mechanochemical effect. Grinding-induced contamination has a significant effect on the oxidation behavior of the system: the impurities incorporated into the sample during grinding in a mill favor complete (WC contamination) or partial (Fe contamination) conversion of hausmannite to kurnakite. Hausmannite contaminated with tungsten carbide oxidizes by a catalytic mechanism. In the case of Fe impurities, oxidation follows a solid-state mechanism, through the formation of restricted Fe_xMn_2?x O₃ solid solutions.     

Accurate measurement of total attenuation coefficient of thin tissue with optical coherence tomography

Noninvasive accurate measurements of tissue optical properties are needed for many diagnostic and therapeutic applications. Optical coherence tomography (OCT) recently proposed for high-resolution imaging in tissue can potentially be applied for accurate, noninvasive, and high-resolution measurement of tissue total attenuation coefficient. However, confocal function (dependence of OCT sensitivity on the distance of probed site from the focal plane of the objective lens) and multiple scattering substantially limit the accuracy of the measurement with the OCT technique. We studied the influence of the confocal function and multiple scattering on the accuracy of the measurement and proposed methods that provide measurement of the total attenuation coefficient with a significantly reduced systematic error. Experiments were performed in tissue phantoms and porcine and human skin in vitro and in vivo. Our data indicate that the tissue total attenuation coefficient can noninvasively be measured in vivo with the accuracy of 5%-10% in the range from 0.5 to 17 mm/sup -1/ and about 20% in the range up to 40 mm/sup -1/. These results suggest that the proper correction of the OCT-based measurement for the confocal function and multiple scattering provides absolute values of tissue total attenuation coefficient with high accuracy and resolution that may not be achievable by other optical techniques in vivo.     

The effect of annealing on the properties of Ga2O3 anodic films

The effect of annealing and oxygen plasma on the electrical characteristics of gallium oxide films has been investigated. Ga₂O₃ films with thicknesses of 200–300 nm were formed by the anodic oxidation of n-GaAs wafers with the donor concentration N _d = (1–2) × 10¹⁶ cm⁻³. It is shown that, after annealing at 900°C for 30 min, the gallium arsenide films contain only the β Ga₂O₃ phase. The effect of the duration of oxygen plasma treatment prior to annealing on the nucleation of β-phase crystallites with different orientations has been studied. It has been established that the electrical conductivity of the Ga₂O₃ films can be managed by annealing and variation in the duration of oxygen plasma treatment. It is shown that the response of the V/Ni-GaAs-Ga₂O₃-V/Ni structure to a mixture exhaled by a person depends on the value and sign of the potential on the control electrode.     

Influence of megaplastic deformation on the structure and hardness of Al–Cu–Mg alloy after aging

Methods of electron microscopy and X-ray diffraction have been used to investigate structural and phase transformations in the aluminum alloy of grade A2024 (Al–4.5 Cu–1.37 Mg–0.61 Mn–0.07 Si–0.27 Fe–0.02 Zn–0.02 Ti (wt %)) after aging and deformation by shear under high quasi-static pressure. It has been shown that the combination of two-stage aging with megaplastic deformation leads to the refinement of the structure to a nanolevel and to strengthening of the alloy (to an increase in the microhardness to 3000 MPa). The values of true deformation at which the deformation-induced dissolution of the particles of the strengthening S phase occurs have been determined.