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    A novel study for supercapacitor applications via corona discharge modified activated carbon derived from Dunaliella salina microalgae
    (Elsevier, 2023) Cetin, Ridvan; Arserim, Muhammet Ali; Akdemir, Murat
    Chemical activation factors including type of chemical agent and amount of agent, as well as carbonization procedures like burning temperature and burning time, have an impact on the surface characteristics of activated carbon. In this study, Dunaliella Salina microalgae was converted to supercapacitor electrode materials for the first time by using multiple parameters such as chemical agent, amount of chemical agent, burning temperature, and burning time, and then new electrode materials were obtained by applying different activation with the help of electrical corona discharge. Dunaliella Salina microalgae were used as activated carbon in accordance with the experimental protocol designed by the Taguchi L9 (3,4) technique. Specific capacitance values of each super-capacitor electrode material were subjected to a linear regression model to determine the effect of each parameter. It has been found that the parameter with the most significant positive effect on the specific capacitance value is the burning temperature. The surface properties of MAD-3, which has the best specific capacitance value of 284.86 F/g, were further improved by being exposed to corona discharge at different frequency values in a two-electrode system. The best specific capacitance value was measured as 335.23 F/g for the MAD-C50 under the condition that the frequency of the application voltage is 50 Hz. In addition, SEM-EDS, and XRD analyses were performed and BET measurements showed that the corona discharge method increased the pore volume and surface area of activated carbon more than 1.6 times.
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    Investigation of Dunaliella salina microalgae as an effective dual-function material for hydrogen production and supercapacitor applications
    (Pergamon-Elsevier Science Ltd, 2024) Cetin, Ridvan; Kaya, Mustafa; Akdemi, Murat; Arseri, Muhammet Ali; Abut, Serdar
    Today, population growth, industrialization and economic growth increase the con-sumption of fossil fuels to meet the energy demand. The scarcity of fossil fuels and the harmful gases they generate increase the interest in renewable energy sources. One of these sources is hydrogen energy, which is plentiful in nature and has no negative envi-ronmental effects. Sodium borohydride (NaBH4) is a good source of hydrogen, but a catalyst must used for methanolysis. Besides producing energy, it is also important to store it. Supercapacitors are a good alternative to energy storage elements due to their outstanding advantages. In this work, Dunaliella salina (DS) microalgae were used as substrate to syn-thesize activated carbon for the first time to develop materials that can operate both as a catalyst and an electrode material for supercapacitors. The activated carbon was obtained by carbonization and activation and the taguchi experimental approach was used to minimize the number of experiments. The best hydrogen production rate (HPR) result for DS-9 catalyst with 0.10 g catalyst and 0.25 g NaBH4 at ambient temperature of 60 degrees C was determined to be 13,085 mL min(-1)gcat(-1). The material with the best HPR value was then used as the electrode material for supercapacitor design. The specific capacitance value for 1 A/g was determined using galvanostatic charge-discharge (GCD) curves to be 216 F/g. In addition, the produced supercapacitor has an energy density of 13.80 W h/kg at a power density of 480 W/kg. The results indicate that the ecologically friendly and cost effective bifunctional materials produced can be used both in reuse of organic wastes and in catalyst and supercapacitor applications. (c) 2023 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.
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    Neuroprotective effects of the combined treatment of resveratrol and urapidil in experimental cerebral ischemia-reperfusion injury in rats
    (Acta Cirurgica Brasileira, 2024) Cetin, Ridvan; Bahadir, Sinan; Basar, Ibrahim; Aslanoglu, Baris; Atlas, Burak; Kaya, Seval; Guzel, Baris Can
    Purpose: To evaluate the neuroprotective effect of resveratrol, urapidil, and a combined administration of these drugs against middle cerebral artery occlusion (MCAO) induced ischemia/reperfusion (IR) injury model in rats. Methods: Thirty-five rats were divided into five groups of seven animals each. Animals in IR, IR resveratrol (IRr), IR urapidil (IRu), and IR + combination of resveratrol and urapidil (IRc) were exposed to MCAO induced cerebral ischemia reperfusion injury model. Rats in IRr and IRu groups received 30-mg/kg resveratrol and 5-mg/kg urapidil respectively. Animals in IRc received a combined treatment of both drugs. At the end of the study, brain tissues were used for oxidative stress (malondialdehyde, glutathione, and superoxide dismutase), pro-apoptotic caspase-3, anti-apoptotic Bcl-2, and pro-inflammatory tumor necrosis factor-alpha cytokine level measurements. Results: The MCAO model successfully replicated IR injury with significant histopathological changes, elevated tissue oxidative stress, and upregulated apoptotic and inflammatory protein expression in IR group compared to control group (p < 0.001). All parameters were significantly alleviated in IRr group compared to IR group (all p < 0.05). In IRu group, all parameters except for caspase-3 and Bcl-2 were also significantly different than IR group (all p < 0.05). The IRc group showed the biggest difference compared to IR group in all parameters (all p < 0.001). The IRc had higher superoxide dismutase and Bcl-2 levels, and lower caspase-3 levels compared to both IRr and IRu groups (all p < 0.05). Also, the IRc group had lower MDA and TNF-alpha levels compared to IRu group (all p < 0.05). Conclusion: The results indicate that combined treatment of resveratrol and urapidil may be a novel strategy to downregulate neurodegeneration in cerebral IR injury.