Physics / Fizik
Permanent URI for this collectionhttps://hdl.handle.net/11147/6
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Article Influence of High Content of Sodium Doping in Bi(pb)2212 Superconductors(Pleiades Publishing, 2023) Faiza, Bouaïcha; Mosbah, Mohamed-Fayçal; Özyüzer, LütfiAbstract: We study here, the effect of high content of sodium doping on structural and electrical properties of Bi(Pb)2212 superconductors. The X-ray analysis results showed that all the prepared samples mainly belong to the superconducting tetragonal phase Bi–(Pb)2212. SEM micrographs show that the grains are closely related and have a characteristic flat shape for the superconductor Bi (Pb) 2212. For the undoped sample, the grains are randomly distributed with an average size of 5 μm. For doped samples, the morphology changes with sodium concentration. Resistivity measurements show that all samples have a superconducting character. © 2023, Pleiades Publishing, Ltd.Article Citation - WoS: 5Citation - Scopus: 5Differences and Similarities in Biophysical and Biological Characteristics Between U87 Mg Glioblastoma and Astrocyte Cells(Springer, 2023) Özdil, Berrin; Çalık Kocatürk, Duygu; Altunayar Ünsalan, Çisem; Açıkgöz, Eda; Oltulu, Fatih; Görgülü, Volkan; Uysal, Ayşegül; Öktem, Gülperi; Ünsalan, Ozan; Güler, Günnur; Aktuğ, HüseyinCurrent cancer studies focus on molecular-targeting diagnostics and interactions with surroundings; however, there are still gaps in characterization based on topological differences and elemental composition. Glioblastoma (GBM cells; GBMCs) is an astrocytic aggressive brain tumor. At the molecular level, GBMCs and astrocytes may differ, and cell elemental/topological analysis is critical for identifying potential new cancer targets. Here, we used U87 MG cells for GBMCS. U87 MG cell lines, which are frequently used in glioblastoma research, are an important tool for studying the various features and underlying mechanisms of this aggressive brain tumor. For the first time, atomic force microscopy (AFM), scanning electron microscopy (SEM) accompanied by energy-dispersive X-ray spectroscopy (EDS), and X-ray photoelectron spectroscopy (XPS) are used to report the topology and chemistry of cancer (U87 MG) and healthy (SVG p12) cells. In addition, F-actin staining and cytoskeleton-based gene expression analyses were performed. The degree of gene expression for genes related to the cytoskeleton was similar; however, the intensity of F-actin, anisotropy values, and invasion-related genes were different. Morphologically, GBMCs were longer and narrower while astrocytes were shorter and more disseminated based on AFM. Furthermore, the roughness values of these cells differed slightly between the two call types. In contrast to the rougher astrocyte surfaces in the lamellipodial area, SEM-EDS analysis showed that elongated GBMCs displayed filopodial protrusions. Our investigation provides considerable further insight into rapid cancer cell characterization in terms of a combinatorial spectroscopic and microscopic approach.Article Citation - WoS: 1Citation - Scopus: 1Hdac9/P300 Immunoexpression and Migration Analysis for Malignant Melanoma Stem Cell(Elsevier, 2023) Özdil, Berrin; Asker Abdikan, Cemile Sinem; Özdemir, Merve; Erişik, Derya; Yesin, Taha Kadir; Avcı, Çığır Biray; Kurkutçu, Yeşim; Güler, Günnur; Aktuğ, HüseyinMelanoma is an aggressive tumor with a poor prognosis that worsens in the metastatic phase. Distruptions of epigenetic mechanisms is known to effect cancer stem cells (CSCs) activity. Malignant melanoma (MM) progression may be promoted by changes in the genetic structure of CSC. Thus, treatments that target epigenetic modifications could be a promising weapon, especially in melanoma. Here, we compared p300, HDAC9, and Factin proteins in melanoma CSCs (CD133+), non-CSCs (CD133-) and CHL-1 cell line, as well as cell migration and division rates. At 4 and 6 h, P300 protein levels in CHL-1 and CD133 + were remarkably similar, and the CD133- showed increases in expression levels as the incubation period lengthened. HDAC9 protein intensity decreased in CHL-1, increased in the CD133-, and remained relatively unchanged in the CD133+ as the incubation period lengthened. The mean value of F-actin expression level increased in all cell group with time, when the highest increase observed in CHL-1. In conclusion, our studies contribute to the management of metastatic diseases in the future and offer new insight into the molecular basis of the initiation and progression of MM.Article A Metric for Gravitational Collapse Around a Schwarzschild Black Hole(World Scientific Publishing, 2023) Erdem, Recai; Demirkaya, Betül; Gültekin, KemalWe consider the problem of gravitational collapse of a fluid under the effect of a small Schwarzschild black hole (e.g. a primordial one). We assume the fluid initially may be approximated by a uniform homogeneous dust. Starting from this configuration we obtain a class of metrics under some physically justified assumptions. We find that the metric we obtain includes the dust collapse as a subcase. After discussing some basic properties of the solution, we discuss the case of dust collapse in more detail. We find that the radial and tangential pressures outside the horizon may take positive or negative values depending on the values of the parameters.Article Citation - WoS: 3Citation - Scopus: 3Compact Multilayer Thin-Film Color Filters and Direct Integration on White-Light Diodes for Color Conversion(Optical Society of America, 2021) Yiğen, Serap; Ekmekçioğlu, Merve; Özdemir, Mehtap; Aygün, Gülnur; Özyüzer, LütfiWe present highly efficient green, yellow, and red filters based on a metal-dielectric structure. The filters encompass only five layers of alternating zinc tin oxide and silver thin films that are grown on soda lime glass and white light-emitting diodes (LEDs) using direct current magnetron sputtering at room temperature. The designed filters provide efficient color filtering in the visible spectrum. High purity colored light is obtained by direct application of filters on LEDs as color converters. The presented method offers an easy way for realizing different colors by tuning the thicknesses of layers in the structure. (C) 2021 Optical Society of America