Development of catalysts for hydrogen generation from hydride compounds

Catalytic hydrolysis of NaBH₄ and NH₃BH₃ has been studied. It was shown that the nature of the support and the active component of the catalyst affect the H₂ generation rate. Despite similar sizes of rhodium particles formed on the surface of different supports (γ-Al₂O₃, TiO₂, carbon), their reactivity is different. Rh/TiO₂ with low rhodium concentration (1 wt.%) is the most active catalyst both in the hydrolysis of NaBH₄ and NH₃BH₃. The obtained results show that the rhodium chloride interaction with titania determines the reactivity of rhodium particles formed under action of NaBH₄ medium. TEM, DRS UV–vis and XPS were used to characterize the catalysts.     

Language learners' digital literacies: Focus on students' information literacy and reading practices online

The widespread use of technology and the Internet have changed many of language learners' everyday practices, including literacies. While there have been many studies with the focus on language learners' digital literacies, few, however, have explored language learners' digital information literacy and online reading practices with the use of social bookmarking tools, especially in a community college setting. We address this gap by investigating community-college language learners' digital literacies when social bookmarking with the focus on digital information and online reading practices from an ecological perspective. In this qualitative multiple-case study, the focal participants were five English learners, students in an English as a Second Language writing course in a community college in the northeastern United States. Data collection included interviews, observations, and researchers' e-journals. Thorough within- and cross-case analysis of data shows that language learners searched for digital texts and evaluated them based on relevance, reliability, interest, language, and importance for them and their learning community in the social bookmarking tool. The participants struggled with the number of results in search engines, keywords, and evaluation of digital texts for relevance and reliability. We show the need for more instruction, support, and guidance of language learners' digital information literacy practices as well as the benefits of providing students with opportunities to read digital texts. Our suggestions for future research include investigating the role of multimodality and other factors that influence language learners' evaluation practices when they look for and read information online.     

Cardioinotropic Effects in Subchronic Intoxication of Rats with Lead and/or Cadmium Oxide Nanoparticles

Subchronic intoxication was induced in outbred male rats by repeated intraperitoneal injections with lead oxide (PbO) and/or cadmium oxide (CdO) nanoparticles (NPs) 3 times a week during 6 weeks for the purpose of examining its effects on the contractile characteristics of isolated right ventricle trabeculae and papillary muscles in isometric and afterload contractions. Isolated and combined intoxication with these NPs was observed to reduce the mechanical work produced by both types of myocardial preparation. Using the in vitro motility assay, we showed that the sliding velocity of regulated thin filaments drops under both isolated and combined intoxication with CdO–NP and PbO–NP. These results correlate with a shift in the expression of myosin heavy chain (MHC) isoforms towards slowly cycling β–MHC. The type of CdO–NP + PbO–NP combined cardiotoxicity depends on the effect of the toxic impact, the extent of this effect, the ratio of toxicant doses, and the degree of stretching of cardiomyocytes and muscle type studied. Some indices of combined Pb–NP and CdO–NP cardiotoxicity and general toxicity (genotoxicity included) became fully or partly normalized if intoxication developed against background administration of a bioprotective complex.     

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.     

Response of Colorado potato beetles,Leptinotarsa decemlineata (Say), to volatile components of tansy,Tanacetum vulgare

The responses of Colorado potato beetle,Leptinotarsa decemlineata (Say), to volatile components of tansy,Tanacetum vulgare L., were investigated in order to establish a chemical basis for observed reduction in beetle populations when potatoes,Solanum tuberosum L., were interplanted with tansy. Colorado potato beetles exhibited avoidance behavior to tansy oil, volatiles from intact tansy plants, a hydrocarbon fraction of tansy oil, obtained by fractionation on alumina, and five of the 13 known components of tansy oil that were tested. One constituent of tansy oil, -pinene, attracted beetles.     

Analysis of the Earthʼs magnetic field variations on the basis of a wavelet-based approach

In the present paper we will discuss a new wavelet-based approach aimed at processing and analyzing different features of complex geomagnetic signals. This approach makes it possible to automatically extract different kinds of disturbances in the Earth?s magnetic field variations, which characterize solar activity and help to predict magnetic storms. In order to analyze geomagnetic signals wavelet packets are used in order to isolate local variations for quiet and perturbed periods and determine their intensity. Furthermore, a new automatic method of calculating the index of geomagnetic activity K is suggested on the basis of forming a quiet-day diurnal variation (Sq-curve). This method allows us to do calculations in the way that is closest to that developed by J. Bartels, who introduced the K-index in 1938. The results are compared with those obtained by INTERMAGNET and the original method of J. Bartels and the advantages of the suggested method are clearly demonstrated. For geomagnetic data collected in high-latitude regions of our planet it has become possible to reduce the error of estimating the K-index by 20% and unlike the technique used by INTERMAGNET here all the calculations can be done automatically. We will use geomagnetic signals that were kindly provided to us by the Institute of Cosmophysical Research and Radio Wave Propagation (Paratunka, Kamchatka region, Far East of Russia) for the period from January, 2002 till December, 2010.     

Structure–properties investigations in hydrophilic nanocomposites based on polyurethane/poly(2–hydroxyethyl methacrylate) semi‐interpenetrating polymer networks and nanofiller densil for biomedical application

Nanocomposites based on sequential semi–interpenetrating polymer networks (semi–IPNs) of crosslinked polyurethane and linear poly(2‐hydroxyethyl methacrylate) filled with 1–15 wt % of nanofiller densil were prepared and investigated. Nanofiller densil used in an attempt to control the microphase separation of the polymer matrix by polymer–filler interactions. The morphology (SAXS, AFM), mechanical properties (stress–strain), thermal transitions (DSC) and polymer dynamics (DRS, TSDC) of the nanocomposites were investigated. Special attention has been paid to the raising of the hydration properties and the dynamics of water molecules in the nanocomposites in the perspective of biomedical applications. Nanoparticles were found to aggregate partially for higher than 3 and 5 wt % filler loading in semi–IPNs with 17 and 37 wt % PHEMA, respectively. The results show that the good hydration properties of the semi–IPN matrix are preserved in the nanocomposites, which in combination with results of thermal and dielectric techniques revealed also the existence of polymer–polymer and polymer–filler interactions. These interactions results also in the improvement of physical and mechanical properties of the nanocomposites in compare with the neat matrix. The improvement of mechanical properties in combination with hydrophilicity and biocompatibility of nanocomposites are promising for use these materials for biomedical application namely as surgical films for wound treatment and as material for producing the medical devises. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43122.