Перегляд за автором "Onishchenko, A."
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Публікація Catalase-like hydrogen peroxide decomposition by GdVO4 :Eu3+ nanocrystals(2024) Maksimchuk, P.; Hubenko, K.; Onishchenko, A.; Seminko, V.; Yefimova, S.Hydrogen peroxide (H2O2) is a member of the reactive oxygen species family and plays a critical role in numerous redox metabolism reactions and cellular processes. It is considered a key component in the homeostatic metabolism of cells, mediating various physiological processes. However, the Fenton reaction between H2 O2 and Fe2+ ions is a major cause of biomolecule oxidation reactions, leading to the formation of highly reactive hydroxyl radicals (•OH). Therefore, there is significant interest in preventive antioxidants that can react with H2O2 without generating free radicals like •OHПублікація Effect of Hydrogen Peroxide Decomposition on Luminescence and Microstructure of GdVO4:Eu3+ Redox-Active Nanocrystals(Institute of Electronics and Computer Sciences, 2024) Hubenko, K.; Maksimchuk, P.; Klochkov, V.; Onishchenko, A.; Yefimova, S.Публікація 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.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.Публікація Fractal and Multi-Fractal Analyses of the Geomagnetic Field Variations Caused by the Earthquake on January 24, 2020 in Turkey(Eskisehir Technical University, 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 the 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 harbingers were revealed. One possible earthquake harbinger in both horizontal components of the geomagnetic field time variations seems to be detected. This harbinger was shown to be registered 25.5 hours before the earthquake event. Being be found in time variations of the multifractal characteristics only for both horizontal components of the geomagnetic field, another possible earthquake harbinger took place 0.5 hours before the earthquake event. The so-called transition of the multifractal process to the mono-fractal mode was detected. For both harbingers, the time-frequency, fractal and multifractal characteristics were estimated.Публікація GdVO4:Eu3+ Nanocrystals as catalase mimics for hydrogen peroxide decomposition(Ivan Franko National University of Lviv, 2024) Maksimchuk, P.; Hubenko, K.; Onishchenko, A.; Kavok, N.; Dudetskaya, G.; Seminko, V.; Yefimova, S.Hydrogen peroxide (H2O2) belongs to the family of reactive oxygen species and is vital for many redox metabolic reactions and cellular activities. It plays an important role in maintaining cellular homeostasis and influencing various physiological functions [1]. However, the reaction known as Fenton's reaction, which occurs between H2O2 and Fe2+ ions, is a significant contributor to the oxidation of biomolecules, resulting in the production of highly reactive hydroxyl radicals (•OH). This has led to increased interest in the development of preventive antioxidants that can interact with H2O2 without forming harmful radicals such as •OHПублікація Hydrogen Peroxide Detection Using Reversible Luminescent CeO2-x and CeO2-x:Eu3+ Nanocrystals(Institute of Physics of the National Academy of Sciences of Ukraine, Taras Shevchenko National University of Kyiv Ukrainian, Physical Society, 2024) Maksimchuk, P.; Neuhodov, Y.; Hubenko, K.; Onishchenko, A.; Kavok, N.; Dudetskaya, G.; Kot, Y.; Yefimova, S.; Seminko, V.Hydrogen peroxide (HP) is a prevalent industrial chemical used extensively for bleaching, cleaning, and disinfection. In biological systems, HP acts as a crucial signaling molecule and is involved in various enzymatic processes as a substrate or byproduct, such as those involving catalase, superoxide dismutase, and numerous oxidases and peroxidases [1, 2]. Thus, precise HP sensing is vital for monitoring its concentration in both industrial and biological contextsПублікація 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.The efficiency of reactive oxygen species scavenging by titanium oxide nanocrystals in water solutions is close to that of nanoceria (CeO2-x nanocrystals) of the same size suggesting that titanium oxide nanoparticles can be effective as an antioxidant in living cells as well. Moreover high biocompatibility of synthesized nanocrystals could be associated with their reactive oxygen species scavenging ability, which make them a prospective material for biomedical applications.Публікація 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.The efficiency of hydroxyl radicals scavenging by small oxide nanocrystals with variable valence ions (CeO2, GdYVO4 and TiO2) in water solutions allows suggesting such materials as effective antioxidants in living cells as well.Публікація Radioprotective Properties of Oxide Nanocrystals(University of Milano, 2024) Hubenko, K.; Maksimchuk, P.; Klochkov, V.; Bespalova, I.; Onishchenko, A.; Demchenko, L.; Yefimova, S.Публікація 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 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•-) inenzyme-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 canexplain the non-trivial anti-aging and radioprotectiv effects of gadolinium-yttrium orthovanadate nanocrystals observedearlier in vivo.Публікація Reversible luminescent hydrogen peroxide sensors based on CeO2-x and CeO2-x:Eu3+ nanocrystals(B. Verkin Institute for Low Temperature Physics and Engineering of NAS Ukraine, 2024) Maksimchuk, P.; Neuhodov, Y.; Hubenko, K.; Onishchenko, A.; Yefimova, S.; Seminko, V.Hydrogen peroxide (HP) is a widespread industrial chemical widely used for bleaching, cleaning, and disinfection. HP also plays an indispensable role in living organisms being a ubiquitous cell signaling molecule [1] and a substrate or byproduct of a number of enzymes (including catalase, superoxide dismutase, and a number of oxidases and peroxidases) [2]. So, HP sensing is required for reliable quantification of HP content in these systems.Публікація Time-Frequency and Fractal Analyses of the Earth's Magnetic Field Variations Appeared During Powerful Geospace Storms Took Place in September 2017(Taras Shevchenko National University of Kyiv Astronomical Observatory, 2021) Chernogor, L.; Lazorenko, O.; Onishchenko, A.According to the non-linear and the system paradigms, many processes generated in open, non-linear, dynamical systems under influence of a powerful source of energy release are appeared to be short-time, ultrawideband, non-linear and fractal.