Yazar "Durmus, Sefa" seçeneğine göre listele

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    Anion effect on magnetic and structural properties of green synthesized NiO nanoparticles via Ni.salt precursors in Salvia officinalis extract
    (Chinese Chemical Soc, 2024) Zenkin, Kubra; Dalmaz, Aslihan; Ozdincer, Mesut; Durmus, Sefa
    Using a green synthesis method, Salvia officinalis extract was used as a reducing and capping agent to synthesize nickel oxide nanoparticles (NiO NPs). In addition, NiO NPs were synthesized using various precursors, and their morphologies were analyzed using scanning electron microscopy. The structures of NiO NPs were characterized using Fourier-transform infrared spectroscopy, and powder X-ray diffraction (PXRD). Their magnetic properties were measured using a vibrating sample magnetometer. PXRD studies showed that all synthesized NiO NPs exhibited a face-centered cubic phase with high crystallinity, and NiO formations with a high-purity phase were confirmed. As a result of magnetization studies, NiO NPs synthesized from three nickel salt precursors (acetate, chloride, and sulfate) exhibit superparamagnetic, soft ferromagnetic, and paramagnetic behaviors, respectively.
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    Biological evaluation of benzothiazoles obtained by microwave-green synthesis
    (Acad Brasileira De Ciencias, 2024) Ozdincer, Mesut; Dalmaz, Aslihan; Durmus, Sefa; Dülger, Görkem; Kiliccioglu, Ilker
    Benzothiazole compounds are known as an important bicyclic ring system with multiple applications. These compounds have a wide range of biological activities, including anticancer, antimicrobial, anti-inflammatory and antiviral activities. In this study, benzothiazole compounds were synthesized and their various biological activities were examined. The synthesized benzothiazoles were evaluated for their antimicrobial properties against various bacterial and fungal strains. The compound 6e is most active ligand in the series against bacteria and fungi as compared to standard antibiotics. Especially, this compound significant effect against Staphylococcus aureus (32.00 +/- 1.73 mm). These compounds exhibited potent anticancer activity against gastrointestinal cancer cells, demonstrating their potential as therapeutic agents. The lowest antiproliferative response after administration of the compounds was observed in HCT116 cells, while the most effective antiproliferative response was observed in AGS cells (> 10 mu g/mL). In all cell lines, 40 and 100 mu g/mL application values of the selected compounds showed significant increases in the expression of caspase-3, 8 and 9. We also utilized a computational docking approach to investigate the interaction of these benzothiazoles with VEGFR-2 kinase. Our docking studies showed that compounds 6a and 6d may be promising therapeutic agents against gastrointestinal system cancers due to their ability to bind to VEGFR-2 kinase.
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    Construction of core@shell NiCo2S4@conductive polythiophene nanocone arrays on carbon cloth for high-performance supercapacitors
    (Elsevier, 2025) Dogramaci, Ozlem Budak; Zenkin, Kuebra; Durmus, Sefa; Bilici, Ali; Koca, Atif
    In recent years, flexible and portable supercapacitor devices have become a focus of attention in the field of energy storage. However, challenges in the selection and preparation of appropriate electrode materials remain. The hierarchical constructing of conducting polymer@transition metal sulfide composites on the flexible carbon cloth substrate is an effective strategy to achieve high-performance supercapacitors. In here, highly conductive polythiophene (Pth) nanocone arrays are hierarchically constructed on the NiCo2S4 (NCS) coated carbon fiber cloth (CC). The modification of NCS electrode surface with conductive polythiophene (Pth) layer (about 6.21 S/ cm) is based on a facile dip-coating process. This facile process allows the formation a conductive polythiophene (Pth) layer on the NCS nanoneedles by protecting porous NCS morphology. Pth shell not only increases the conductivity of NCS electrode but also alleviates agglomeration during charge-discharge process. The synergistic effect between NCS and Pth improves the capacitive characteristics of electrode. Compared to NCS@CC and Pth@CC electrodes, NCS@Pth(0.3)@CC composite electrode exhibits a superior specific capacitance (1632.8 F g-1 impressive results emphasize the potential of the newly developed hybrid structure as a high-performance electrode material for electrochemical devices. at 1 A g-1 of current density) and an outstanding retention stability (90.1 % after 5000 cycles). These
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    Fabrication, characterization and corrosion inhibition properties of SCW-based ZnO nanofluids
    (Taylor & Francis Inc, 2024) Ozdincer, Mesut; Durmus, Sefa
    Nanofluids have demonstrated incredible potential for application in various industries such as coolants. Metal oxides are widely used as solid particles in formulations of nanofluids due to their advantages. Metal oxide-based nanoparticles (NPs), ZnO NPs were fabricated by the ultrasonically assisted co-precipitation method. The structure and morphology of the synthesized ZnO NPs were characterized using an array of analytical techniques including X-ray powder diffraction (XRD) and scanning electron microscopy (SEM). The XRD results showed that the purity of ZnO was obtained. The investigated nanofluids remained stable for a long time without substantial sedimentation. The present study deals with the corrosion assessment of St37 steel in nanofluids prepared with various concentrations of ZnO NPs. A scanning electron microscope coupled with energy-dispersive X-ray spectroscopy was used to determine the surface characteristics and elemental composition of low-carbon steel specimens both before and after corrosion tests. Notably, the nanofluid containing 0.05% by weight of ZnO nanoparticles demonstrated the highest corrosion prevention efficiency among the prepared nanofluids. Furthermore, impedance spectroscopy measurements revealed that the corrosion resistance increased by 72.9% for the nanofluid containing 0.05 wt% ZnO NPs compared to the base fluid. These findings highlight the potential of ZnO nanoparticles as an environmentally friendly anti-corrosion compound in cooling systems, effectively reducing corrosion degradation.
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    Investigating Magnetic, Dielectric, Optic And Morphologic Properties Of Nano-Nickel Oxide-Doped Ndfeo3
    (World Scientific Publ Co Pte Ltd, 2024) Zenkin, Kubra; Durmus, Sefa; Demir, Ahmet
    In this investigation, alpha-Fe2O3 was prepared via co-precipitation and nano-NiO and NdFeO3 were synthesized using the sol-gel method. For NdFe0.50.5Ni0.50.5O(3) synthesis, Nd(2)O3,alpha 3,-Fe2O3, and nano-NiO compounds were mixed via the solid state method. The effect of each component and that of nano-NiO on the NdFe0.50.5Ni0.50.5O(3) crystal properties was characterized by using X-ray diffraction (XRD), scanning electron microscopy-energy dispersive X-ray (SEM-EDX), ultraviolet-visible (UV-Vis), vibrating sample magnetometer (VSM), impedance and bandgap analyses. The orthorhombic perovskite structure was confirmed by the XRD data. With the doping of nano-NiO, the unit cell volume was found to decrease. The UV-Vis spectroscopy showed that the nano-NiO-doped optical bandgap (E-g) had increased. The VSM analysis demonstrated that by doping nano-NiO to weak ferromagnetic NdFeO3, the resulting NdFe0.50.5Ni0.50.5O(3) was rendered superparamagnetic. The real and imaginary parts of dielectric permittivity (epsilon '' and epsilon '''') and the loss tangent (tan delta) characteristic of the compounds were measured at AC-signaled frequencies of 100 Hz-10 MHz and a voltage range of 0-20 V DC. The increase in active charge transmission with the doping of nano-NiO reduced the epsilon '' values. In addition, the large differences between the epsilon '' values were thought to be caused by the breakdown voltage (E-b) effect of the compounds. The epsilon '''' and tan delta changes revealed the dipole formation of the compounds at different voltages, their relaxation regions and their polarization mechanism type. The dielectric loss behavior of the compounds demonstrated their good dielectric material properties. This study investigated the effect of method difference and doped material particle size on magnetic and dielectric properties.
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    Salvia officinalis leaf extract-stabilized NiO NPs, ZnO NPs, and NiO@ZnO nanocomposite: Green hydrothermal synthesis, characterization and supercapacitor application
    (Springer Heidelberg, 2024) Zenkin, Kuebra; Durmus, Sefa; Emre, Deniz; Bilici, Ali; Yilmaz, Selehattin
    In this study, NiO nanoparticles (NiO NPs) and NiO@ZnO nanocomposite were synthesized for the first time using a Salvia officinalis (S. officinalis) extract-assisted hydrothermal process. The S. officinalis leaf extract served as a natural reducing and capping agent. The synthesized NiO NPs, ZnO NPs, and NiO@ZnO nanocomposite were thoroughly characterized using various techniques, including Fourier-transform infrared spectroscopy (FT-IR), ultraviolet-visible spectroscopy (UV-Vis), powder X-ray diffraction (PXRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy (EDX), energy-dispersive spectrometry (EDS) mapping, vibrating sample magnetometer (VSM), and cyclic voltammetry (CV) analysis. The direct and indirect band gap energies of NiO NPs, ZnO NPs, and NiO@ZnO were found to be 3.00, 2.28, and 2.71 eV, and 2.63, 1.91, and 2.23 eV, respectively. The crystallite sizes were analyzed using PXRD spectra through Scherrer and Williamson-Hall (W-H) methods. TEM analysis revealed that the average particle sizes of NiO NPs, ZnO NPs, and NiO@ZnO were 16.0, 207.5, and 31.0 nm, respectively. The magnetic properties of all nanomaterials were assessed via the VSM technique. Specific capacitance (Cs) values, determined from CV voltammograms, were 196.8, 632.4, and 785 Fg-1 at a scan rate of 25 mVs-1 for NiO NPs, ZnO NPs, and NiO@ZnO, respectively. These findings suggest that the green-synthesized NiO@ZnO nanocomposite holds significant potential as a high-performance electrode material for supercapacitor applications.
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    Treatment of silicate Ion with Bacillus subtilis bacteria in demineralization-water/steam cycles in power plants
    (2025) Bozkurt, Deniz; Dalmaz, Aslihan; Durmus, Sefa
    Inorganic silica and various mineral deposits are particularly important in the process waters of power plants. The presence of these inorganic species, especially silica, poses many challenges for process water applications in power plants. If silica in process waters is not controlled, it forms hard, difficult, and dangerous deposits for process water. Silica formation and accumulation cannot be prevented by many conventional methods and scale inhibitors. In this study, Bacillus subtilis bacteria was used to minimize silica formation in the process water of power plants. For this purpose, many different parameters were optimized in the system steps. The results obtained are promising for the use of silica removal in process water applications. In addition, the use of Bacillus subtilis bacteria for the treatment of process water will provide significant economic benefits. Therefore, this study will make an important contribution to the literature and will be very advantageous in terms of cost for various industrial organizations that face silica problems in process waters.