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    Ecotoxicological Effects of Titanium Aluminum Carbide Composites on Biochemical and Metabolic Parameters of Galleria mellonella
    (Springer, 2023) Sugecti, Serkan; Akbayrak, Serdar; Buyukguzel, Ender; Buyukguzel, Kemal
    Metal composites have been extensively used in various fields such as automotive industry, medicine and pharmacy. However, the high exposure of these chemicals may have an adverse effect on the living organisms. In this study, the effect of titanium aluminum carbide (Ti3AlC2) on the model organism Galleria mellonella was investigated. The change in the metabolic enzymes such as alanine transferase, aspartate transferase, gamma-glutamyl transferase, lactate dehydrogenase, amylase, creatine kinase, alkaline phosphatase in the hemolymph of G. mellonella which was exposed to Ti3AlC2 was determined. The contents of the bilirubin, albumin, uric acid and the total protein were also measured after the Ti3AlC2 exposure on the model organism. The results of our study clearly indicate that Ti3AlC2 has adverse effects on the model organism G. mellonella.
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    Magnetically Isolable Pt0/Co3O4 Nanocatalysts: Outstanding Catalytic Activity and High Reusability in Hydrolytic Dehydrogenation of Ammonia Borane
    (Amer Chemical Soc, 2021) Akbayrak, Serdar; Ozkar, Saim
    The development of a new platinum nanocatalyst to maximize the catalytic efficiency of the precious noble metal catalyst in releasing hydrogen from ammonia borane (AB) is reported. Platinum(0) nanoparticles are impregnated on a reducible cobalt(II,III) oxide surface, forming magnetically isolable Pt-0/Co3O4 nanocatalysts, which have (i) superb catalytic activity providing a record turnover frequency (TOF) of 4366 min(-1) for hydrogen evolution from the hydrolysis of AB at room temperature and (ii) excellent reusability, retaining the complete catalytic activity even after the 10th run of hydrolysis reaction. The outstanding activity and stability of the catalyst can be ascribed to the strong interaction between the platinum(0) nanoparticles and reducible cobalt oxide, which is supported by the results of XPS analysis. Pt-0/Co3O4 exhibits the highest TOF among the reported platinum-nanocatalysts developed for hydrogen generation from the hydrolysis of AB.
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    Magnetically separable nickel ferrite supported palladium nanoparticles: Highly reusable catalyst in Sonogashira cross-coupling reaction
    (Academic Press Inc Elsevier Science, 2022) Keskin, Selbi; Citlakoglu, Meryem; Akbayrak, Serdar; Kaya, Serdal
    There is an increasing attention in developing highly efficient and reusable palladium-based catalysts used for the coupling reactions due to the high cost of palladium metal salts. Magnetically separable palladium nanoparticles have a high potential to be used as catalysts in numerous organic reactions due to their facile separation from the reaction medium by an external magnet. Herein, NiFe2O4 supported palladium nanoparticles (Pd/NiFe2O4) were successfully prepared by impregnation and reduction method in water and used as catalysts for Sonogashira cross-coupling reactions. Magnetically separable Pd/NiFe2O4 catalysts were found to be highly active and reusable in this reaction. Pd/NiFe2O4 provided an outstanding turnover frequency value (106.4 h(-1)) in the reaction between phenylacetylene and iodobenzene in ethanol at 70 degrees C and it was also found to be highly active in the water. Magnetically separable Pd/ NiFe2O4 exhibited high catalytic performance even after the tenth use in this reaction. (C) 2022 Elsevier Inc. All rights reserved.
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    Palladium nanoparticles supported on cobalt(II,III) oxide nanocatalyst: High reusability and outstanding catalytic activity in hydrolytic dehydrogenation of ammonia borane
    (Academic Press Inc Elsevier Science, 2022) Akbayrak, Serdar; oezkar, Saim
    A new palladium(0) nanocatalyst is developed to enhance the catalytic efficiency of precious metal catalysts in hydrogen generation from the hydrolytic dehydrogenation of ammonia borane. Magnetically separable Pd-0/Co3O4 nanocatalyst can readily be obtained by the reduction of palladium(II) cations impregnated on cobalt(II, III) oxide at room temperature. The obtained Pd-0/Co3O4 nanocatalyst with 0.25% wt. palladium loading has outstanding catalytic activity with a record turnover frequency of 3048 min(-1) in the releasing H-2 from the hydrolysis of ammonia borane at 25.0 degrees C. They also provide out-standing reusability even after the tenth run of the hydrolysis of ammonia borane at 25.0 degrees. The high activity and superb stability of magnetically isolable Pd-0/Co3O4 nanoparticles are attributed to the favor-able interaction of palladium with the surface of reducible cobalt oxide. (C) 2022 Elsevier Inc. All rights reserved.
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    Reducible tungsten(VI) oxide-supported ruthenium(0) nanoparticles: highly active catalyst for hydrolytic dehydrogenation of ammonia borane
    (Tubitak Scientific & Technological Research Council Turkey, 2023) Akbayrak, Serdar; Tonbul, Yalcin; Ozkar, Saim
    Reducible WO3 powder with a mean diameter of 100 nm is used as support to stabilize ruthenium(0) nanoparticles. Ruthenium(0) nanoparticles are obtained by NaBH4 reduction of ruthenium(III) precursor on the surface of WO3 support at room temperature. Ruthenium(0) nanoparticles are uniformly dispersed on the surface of tungsten(VI) oxide. The obtained Ru0/WO3 nanoparticles are found to be active catalysts in hydrolytic dehydrogenation of ammonia borane. The turnover frequency (TOF) values of the Ru0/WO3 nanocatalysts with the metal loading of 1.0%, 2.0%, and 3.0% wt. Ru are 122, 106, and 83 min-1, respectively, in releasing hydrogen gas from the hydrolysis of ammonia borane at 25.0 degrees C. As the Ru0/WO3 (1.0% wt. Ru) nanocatalyst with an average particle size of 2.6 nm provides the highest activity among them, it is extensively investigated. Although the Ru0/WO3 (1.0% wt. Ru) nanocatalyst is not magnetically separable, it has extremely high reusability in the hydrolysis reaction as it preserves 100% of initial catalytic activity even after the 5th run of hydrolysis. The high activity and reusability of Ru0/WO3 (1.0% wt. Ru) nanocatalyst are attributed to the favorable metal-support interaction between the ruthenium(0) nanoparticles and the reducible tungsten(VI) oxide. The high catalytic activity and high stability of Ru0/WO3 nanoparticles increase the catalytic efficiency of precious ruthenium in hydrolytic dehydrogenation of ammonia borane.