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Öğe Experimental and theoretical characterization of Dy-doped hydroxyapatites(Springer, 2023) Isen, Fatih; Kaygili, Omer; Bulut, Niyazi; Ates, Tankut; Osmanlioglu, Fatih; Keser, Serhat; Tatar, BeyhanThe effects of adding Dy to the hydroxyapatite (HAp) structure were investigated experimentally and theoretically. The as-obtained experimental results with an increasing amount of Dy are as follows. X-ray diffraction, Raman, and Fourier transform infrared measurements verified the HAp structure for each specimen. The crystallinity, lattice parameters, lattice stress, strain, and anisotropic energy density were affected. Thermal stability and stoichiometry were not affected. It was observed that all the Dy-doped HAps have smaller crystallite size values compared to the un-doped HAp. The cell viability obtained from mouse fibroblast cell (L929) was higher than 82%, indicating all the samples were biocompatible. The theoretical findings, obtained from the density functional theory (DFT) calculations, exhibited a continuous decrease in the bandgap from 4.7109 to 3.7982 eV, an increase in the density from 3,155 to 3,189 kg m(-3), and an increase in the linear absorption coefficient.Öğe In vitro Biological Activities and Phytochemical Contents of Portulaca oleracea L. (Purslane)(Niyazi BULUT, 2021) Keser, Fatma; Karatepe, Mustafa; Keser, Serhat; Tekin, Suat; Türkoğlu, İsmail; Kaygili, Omer; Demir, ErsinP. oleracea is an annual herbaceous plant, belonging to the Portulaceae family. This plant is consumed as a vegetable in Turkey, and is grows spontaneously in wetlands, along streams and meadows. In this study, the antiradical, antimicrobial, anticancer activities and phytochemical contents of aerial parts extracts of P. oleracea were investigated. According to study results, P. oleracea aerial part extracts show very high anticancer activity against MCF-7, HCT-116, A2780 and PC-3 cancer cell lines, high antiradical activity against OH radicals, and effective antimicrobial activity against some microorganisms. Also, it was determined that P. oleracea aerial parts contain highly phytochemical compounds. In conclusion, it can be said that the P. oleracea aerial parts can be used for antiradical, antimicrobial, anticancer purposes.Öğe Malva neglecta Wallr. (Ebegümeci)’nın In vitro Biyoaktif ve Fitokimyasal Özellikleri(Düzce Üniversitesi, 2022) Keser, Fatma; Karatepe, Mustafa; Keser, Serhat; Tekin, Suat; Türkoğlu, İsmail; Kaygili, Omer; Demir, ErsinM. neglecta çok yıllık otsu bir bitkidir ve Malvaceae familyasında yer almaktadır. Bu bitki ülkemizde her türlü toprakta kendiliğinden yetişir ve taze sürgünleri ile yaprakları sebze olarak tüketilir. Bu çalışmada M. neglecta toprak üstü kısımlarının su, etanol ve metanol ekstraktlarının antiradikal, antimikrobiyal, antikanser ve fitokimyasal içerikleri incelenmiştir. Elde edilen sonuçlara göre, M. neglecta toprak üstü kısımlarının yüksek antiradikal, antimikrobiyal, antikanser aktiviteye ve fitokimyasal içeriğe sahip olduğu anlaşılmıştır.Öğe Phytochemical compounds and antiradical, antimicrobial, and cytotoxic activities of the extracts from Hypericum scabrum L. Flowers(Taylor & Francis Ltd, 2020) Keser, Serhat; Keser, Fatma; Kaygili, Omer; Tekin, Suat; Demir, Ersin; Turkoglu, Ismail; Kirbag, SevdaHypericum scabrum L. has been widely used in traditional medicine for the treatment of many diseases just as the other Hypericum species. In the present study, the antiradical, antimicrobial and cytotoxic activities of water and ethanol extracts of H. scabrum flowers were investigated. Their phytochemical contents and composition were also determined. The water and ethanol extracts are better scavenged ABTS (97.89 and 98.99%) and OH radicals (96.36 and 97.33%); the water extract is better scavenged DPPH radicals (91.66%) than the standard antioxidant BHA (94.33, 85.19, 90.16%, respectively). Flowers of H. scabrum contain flavonoids, phenolic acids, vitamins and phytosterols, dominated by catechin, vanillic acid, vitamin K and ergosterol. The extracts exhibit a strong cytotoxic activity against MCF-7, HCT-116, and LNCaP cancer cell lines. It is found that their antimicrobial activities are higher than the standard antibiotics. These results indicate that H. scabrum flowers have potent antiradical, antimicrobial and cytotoxic activities.Öğe Structural, optical, and electrical investigation of multilayered MnO2(n)/ NiO(p) heterojunctions for supercapacitors applications(Elsevier, 2023) Alanazi, Maha; Ghrib, Taher; Ercan, Filiz; Alsubaie, Mizna; Demirci, Tuna; Kaygili, Omer; Kayed, Tarek S.Heterojunctions of alternating MnO2 and NiO thin films were deposited on an Indium Tin Oxide (ITO). The MnO2 and NiO thin films were synthesized by electrodeposition and sol-gel methods respectively. The structural morphology of the synthesized heterojunctions was investigated by scanning electron microscopy (SEM) and atomic force microscopy (AFM). The microstructural and chemical compositions were examined by X-ray diffraction (XRD), Fourier transform infrared (FTIR), and Raman techniques. The optical properties were investigated by Ultraviolet-Visible (UV) analysis. The electrical conductivity, specific capacitance, and charge carrier density were determined using the Hall effect and Electrochemical impedance spectroscopy (EIS) methods. As a result, it was found that the MnO2 and NiO thin films crystallize in tetragonal and cubic crystal systems respectively. Increasing the number of NiO/MnO2 heterojunctions increases the electrical conductivity from 9.7 x 10- 7 to 1.2 x 10-3 S.cm- 1, the bandgap decreased 3.16 to 2.62 eV, the volume carrier density rises from 5.17 x 1011 to 4.62 x 1012 cm-3. The specimens constituted of two and four alternative staked MnO2 and NiO layers are characterized by a specific capacitance of 3.6 x 103 and 5.8 x 103 F.g -1 and capacitance retention of 14.8 and 12.9% which consider them promising materials for supercapacitor devices.Öğe Structural, spectroscopic, dielectric, and magnetic properties of Fe/Cu co-doped hydroxyapatites prepared by a wet-chemical method(Elsevier, 2022) Ercan, Ismail; Kaygili, Omer; Kayed, Tarek; Bulut, Niyazi; Tombuloglu, Huseyin; Ince, Turan; Koysal, OguzIn this study, the effects of Cu and Fe additives on the structural, dielectric, magnetic, thermal and morphology of hydroxyapatite (HAp) samples were investigated and reported in detail for the first time. The prepared systems were also modeled and examined theoretically. It can be said that both additives affect the thermal behavior of the HAp structure. The addition of Cu affected the morphology of submicron-sized particles with spherical-like shapes with a low degree of agglomeration. Diffuse reflection data revealed that the energy band gap values decreased as Cu was added to the Fe-based HAp structure. The dielectric constant (epsilon') had high values at low frequencies in all samples and decreased with increasing frequency. It could be concluded that Fe/Cu incorporation to hydroxyapatites enhanced its thermal, magnetic, and dielectric properties required for mimicking natural HAps to open a successful venue for medical application in the healing regeneration of bone.
