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  • Документ
    Hydroxyl radical scavenging activity of titanium oxide nanocrystals
    (2022) Maksimchuk, P.; Hubenko, K.; Seminko, V.; Onishchenko, A.; Bespalova, I.; Onishchenko, A.; Prokopiuk, V.; Tkachenko, A.; Yefimova, S.
  • Документ
    Reactive Oxygen Species Scavenging by Small Gadolinium-Yttrium Orthovanadate Nanocrystals
    (2022) Maksimchuk, P.; Hubenko, K.; Seminko, V.; Onishchenko, A.; Aslanov, A.; Klochkov, V.
    Oxidative stress induced by reactive oxygen species (hydrogen peroxide, superoxide anion, hydroxyl radical etc.) is the key factor in developing a variety of pathological conditions including diabetes, asthma, atherosclerosis, hypertension mellitus and cancer. To prevent or reduce the cell damages caused by reactive oxygen species, natural or synthetic molecules named antioxidants are commonly used. Recently, various inorganic nanomaterials, such as CeO2, Mn3O4, Co3O4 and Fe3O4 nanocrystals, have attracted growing interest as nano-antioxidants with reactive oxygen species regulating ability. Here, we report on high antioxidant behavior of small gadolinium-yttrium orthovanadate nanocrystals revealed by spectroscopic methods using various reactive oxygen species sensors, and propose the mechanism describing their reactive oxygen species scavenging action. It has been found that in 2 nm gadolinium-yttrium orthovanadate nanocrystals more than 60% vanadium ions are presented in lower V4+ and V3+ oxidation states. Switching between V3+↔V4+ and V4+↔V5+ oxidation states allow gadolinium-yttrium orthovanadate nanocrystals to react with hydrogen peroxide (H2O2) and superoxide anion (O2 •-) in enzyme-like manner and neutralize hydroxyl radical (•OH), and peroxyl radicals (ROO•), as well. The obtained data and proposed mechanism of gadoliniumyttrium orthovanadate nanocrystals antioxidant action can explain the non-trivial anti-aging and radioprotective effects of gadolinium-yttrium orthovanadate nanocrystals observed earlier in vivo.
  • Документ
    Hydroxyl radicals scavenging by small oxide | nanocrystals with variable valence ions
    (Nanocomposites and Nanomaterials, 2022) Maksimchuk, P.; Hubenko, K.; Seminko, V.; Onishchenko, A.; Bespalova, I.; Klochkov, V.; Yefimova, S.
  • Документ
    Fractal and Multi-Fractal Analyses of the Geomagnetic Field Variations Caused by the Earthquake on January 24, 2020 in Turkey
    (2022) Onishchenko, A.; Chernogor, L.; Lazorenko, O.
    Fractal and multi-fractal properties of the Earth’s magnetic field time variations caused by the earthquake took place on January 24, 2020 in Turkey were investigated. Using Dynamical Fractal Analysis method proposed by the authors for both (D and H) horizontal components of geomagnetic field, the time dependences for the Hurst fractal dimension were obtained. With usage of the Wavelet Transform Module Maxima method and the Multi-Fractal Detrended Fluctuation Analysis method, the set of traditional and original multi-fractal numerical characteristics was estimated. Combining the fractal and multi-fractal analyses results with ones for the time-frequency structure, obtained the Continuous Wavelet Transform application, the set of disturbances caused by the earthquake was discovered. For these disturbances, all needed time-frequency, fractal and multifractal characteristics were estimated. The disturbances were shown to be fractal ultra-wideband processes with complex, non-stationary multi-fractal structure. Two promising candidates for the role of earthquake precursors were revealed. One possible earthquake precursor in both horizontal components of the geomagnetic field time variations seems to be detected. This precursor was shown to be registered 25.5 hours before the earthquake event. Being be found in time variations of the multi-fractal characteristics only for both horizontal components of the geomagnetic field, another possible earthquake precursor took place 0.5 hours before the earthquake event. The so-called transition of the multi-fractal process to the monofractal mode was detected. For both precursors, the time-frequency, fractal and multifractal characteristics were estimated.
  • Документ
    Кубическая резонансная решетка металлических сфер в магнитодиэлектрической среде
    (ХНУРЕ, 2019) Кулак, Г. К.
    The solution and analysis of a problem are considered concerning plane wave scattering by a resonance lattice of spherical particles located in magnetodielectric medium.