Yazarlar
Yayınlar
- MakaleYalnız künye2026Scopus SJRQ2Influence of holmium substitution on structural characteristics and radiation shielding parameters of YBCO (358) superconducting ceramics
Düzgün, İbrahim; Kaya, Selim; Gül, Osman
This study reports on the structural characterization, radiation shielding assessment, and magnetic-field response of holmium-substituted Y3-xHoxBa5Cu8O18+δ superconducting ceramics synthesized by the conventional solid-state reaction route. X-ray diffraction measurements on five compositions (x = 0, 0.75, 1.5, 2.25, 3) supported the formation of a dominant orthorhombic Y358-type matrix across the substitution range. Scanning electron microscopy (SEM) combined with energy-dispersive X-ray spectroscopy (EDS) revealed a progressive microstructural evolution with increasing Ho content, including SEM–BEC/EDS-detectable Ho-rich inclusions consistent with Ho2BaCuO5-type secondary particles at higher substitution levels. XCOM-based mass attenuation coefficients, half-value layer, mean free path, effective atomic number, radiation protection efficiency, gamma-ray kerma coefficients, and fast-neutron removal cross-sections were calculated for all five compositions over 50–2000 keV. EGS4 Monte Carlo simulations independently verified the XCOM results for three representative compositions (x = 0, 1.5, and 3). Ho-containing specimens exhibited a significant enhancement in photon absorption near 60 keV, associated with the increased photoelectric contribution of holmium in the vicinity of its K-absorption edge. Among the full five-composition series, the x = 2.25 specimen (ρ = 5.531 g cm−3) exhibited the best calculated shielding performance across the full energy range, owing to its highest bulk density combined with substantial Ho incorporation. The x = 1.5 specimen provided the most balanced calculated radiation-attenuation and hysteretic magnetic response among the three representative compositions examined by EGS4 and M–H measurements at 20 K, retaining approximately 93% of the reference M–H hysteresis area while full substitution reduces it by roughly 67%. These findings establish a multi-parametric reference dataset for Ho-substituted Y358 ceramics and demonstrate the promise of rare-earth-engineered superconducting ceramics as multifunctional materials in radiation-intensive environments.
- MakaleAçık Erişim2024Scopus SJRQ3Characterization of Water-Soluble Extracellular Polysaccharide from Aeribacillus pallidus IM17
Genc, Berna; Tunç, Merve Tuğçe; Adiguzel, Ahmet
The production of the extracellular polysaccharide from the thermophilic bacterium Aeribacillus pallidus was carried out in the study. The polysaccharide was isolated and characterized by means of GC–MS, FT-IR, DSC, and XRD analyses. The rheological, foaming, and emulsifying properties of the polysaccharide were determined. Using a sucrose-rich medium, 27.1 mg dried EPS/100 mL was obtained with 94% carbohydrate and 1.5% protein. The monosaccharide profile of water-soluble EPS-IM17 was composed of rhamnose, arabinose, xylose, mannose, glucose, and galactose. The foaming capacity and stability of EPS-IM17 were 26.67% (± 4.71) and 40.01% (± 4.95), respectively, and the foaming stability was not affected by time. The emulsification index of EPS-IM17 was 64.54 (± 8.71) and decreased to 38.47 (± 10.44) after 24 h. EPS-IM17 had a crystalline structure. Solutions at different concentrations (10, 20, 40 mgmL-1) showed pseudoplastic behavior. In conclusion, this report could be a lead study for the use of Aeribacillus pallidus extracellular polysaccharide for different applications.
AtıfScopus5WoS5İncele - MakaleYalnız künye2023Scopus SJRQ3Comparison of Mechanical Properties Obtained for Armor Steels: Conventional Methods vs. Nanoindentation
Ekmekci, Dursun; Cora, Ömer Necati
The mechanical properties of three armor steels, namely Ramor 500, Ramor 550, and Armox Advance, were acquired by nanoindentation and conventional methods, and then the results were compared. To this goal, samples were extracted from different (e.g., undeformed and deformed) zones of the ballistically tested armor plates. Then, nanoindentations were performed at 10-mN maximum load and different maximum indentation depths (50-150 nm). In addition to the hardness and modulus of elasticity values of the examined materials, residual stress values of the samples were calculated through the equations suggested in the literature. These values were then compared with the residual stress measurements obtained with the conventional x-ray diffraction (XRD) - sin2ψ method. Moreover, Charpy V-notch impact tests were performed to calculate the fracture toughness of armor steel samples. Microstructural analysis (e.g., optical microscope, scanning electron microscope, atomic force microscope), surface roughness, and micro-hardness (micro-Vickers) measurements were also obtained. It was noted that hardness values for the Ramor 500 and Ramor 550 armor steels were in the range of 5.5-9 GPa, whereas the hardness values of Armox Advance samples were obtained in the 8.6-10.2 GPa range at a 50-nm indentation depth. The residual stress values obtained with nanoindentation were found to be in quite good agreement with the one obtained through XRD. It was proven that nanoindentation can be used to acquire several mechanical properties through considerably less sample preparation procedure, in an automated, and a more representative manner because of the measurements obtained at multiple points.
- MakaleYalnız künye2007Scopus SJRQ1Availability of tuffs from northeast of Turkey as natural pozzolan on cement, some chemical and mechanical relationships
Çavdar, Ahmet; Yetgin, Şükrü
At Northeast of Turkey, it is possible to find plenty of volcanic origin rocks and rich natural pozzolan beds. In this study, the pozzolanic activities of six types of different tuff samples taken from Trabzon and Bayburt regions (Northeast of Turkey) were examined according to the related standard and it was determined that the compressive strengths were varying between 6.7-11.0 MPa. In addition, the chemical compositions of these samples, except one, were consistent with the related standard. On the other hand, the results obtained from these studies were that increase in the proportion of SiO2 in the pozzolan increases the pozzolanic activity.
AtıfScopus74OpenAlex73İncele