WoS İndeksli Yayınlar Koleksiyonu / WoS Indexed Publications Collection
Permanent URI for this collectionhttps://hdl.handle.net/11147/7150
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Article A Quantitative Description of Barite Thermodynamics, Nucleation and Growth for Reactive Transport Modelling(Elsevier, 2024) Dideriksen,K.; Zhen-Wu,B.Y.; Dobberschütz,S.; Rodríguez-Blanco,J.D.; Raahauge,P.J.; Ataman, Evren; Stipp,S.L.S.The regression of available thermodynamic data in the BaSO4–NaCl–H2O system yielded Pitzer ion interaction parameters that accurately describe the activities of aqueous species and mineral solubilities in this system. This thermodynamics description is compared with published Pitzer parameter sets, and combined with a model for the kinetics of barite nucleation and growth, based on classical nucleation theory. Both the thermodynamic and nucleation/growth models have been incorporated into the PHREEQC computer code to facilitate calculation of the extent and consequences of barite formation in natural and engineered systems. Results of geochemical modelling calculations agree adequately with the amount of barite scale thicknesses derived from calliper measurements from an oil well if the effective surface free energy of barite nuclei is assumed to be ∼50 mJ m−2. Better results, however, are achieved using a temperature dependent effective surface free energy. In contrast, calculations performed by ignoring the effects of barite nucleation lead to a substantial overestimation of the amount of scale formed in our modelled systems. The success of our mineral nucleation and growth model to describe scaling in our modelled system suggests this description of precipitation rates can be applied to many other mineral-aqueous fluid systems, in particular where supersaturation is slight and the solids forming have substantial surface free energy. © 2024 Elsevier LtdArticle Citation - WoS: 1Citation - Scopus: 1Modeling Cosmological Perturbations of Thermal Inflation(IOP Publishing, 2024) Bae, Jeong-Myeong; Hong, Sungwook E.; Zoe, HeeseungWe consider a simple system consisting of matter, radiation and vacuum components to model the impact of thermal inflation on the evolution of primordial perturbations. The vacuum energy magnifies the primordial modes entering the horizon before its domination, making them potentially observable, and the resulting transfer function reflects the phase changes and energy contents. To determine the transfer function, we follow the curvature perturbation from well outside the horizon during radiation domination to well outside the horizon during vacuum domination and evaluate it on a constant radiation density hypersurface, as is appropriate for the case of thermal inflation. The shape of the transfer function is determined by the ratio of vacuum energy to radiation at matter-radiation equality, which we denote by upsilon , and has two characteristic scales, ka and kb , corresponding to the horizon sizes at matter radiation equality and the beginning of the inflation, respectively. If upsilon MUCH LESS-THAN1 , the Universe experiences radiation, matter and vacuum domination eras and the transfer function is flat for kMUCH LESS-THANkb , oscillates with amplitude 1/5 for kbMUCH LESS-THANkMUCH LESS-THANka and oscillates with amplitude 1 for k >> ka . For upsilon >> 1 , the matter domination era disappears, and the transfer function reduces to being flat for kMUCH LESS-THANkb and oscillating with amplitude 1 for k >> kb .Article Citation - WoS: 9Citation - Scopus: 8Chlorinated Phosphorene for Energy Application(Elsevier, 2024) Hassani, Nasim; Yağmurcukardeş, Mehmet; Peeters, Francois M.; Neek-Amal, MehdiThe influence of decoration with impurities and the composition dependent band gap in 2D materials has been the subject of debate for a long time. Here, by using Density Functional Theory (DFT) calculations, we systematically disclose physical properties of chlorinated phosphorene having the stoichiometry of PmCln. By analyzing the adsorption energy, charge density, migration energy barrier, structural, vibrational, and electronic properties of chlorinated phosphorene, we found that (I) the Cl-P bonds are strong with binding energy Eb =-1.61 eV, decreases with increasing n. (II) Cl atoms on phosphorene have anionic feature, (III) the migration path of Cl on phosphorene is anisotropic with an energy barrier of 0.38 eV, (IV) the phonon band dispersion reveal that chlorinated phosphorenes are stable when r <= 0.25 where r = m/n, (V) chlorinated phosphorenes is found to be a photonic crystal in the frequency range of 280 cm-1 to 325 cm-1, (VI) electronic band structure of chlorinated phosphorenes exhibits quasi-flat bands emerging around the Fermi level with widths in the range of 22 meV to 580 meV, and (VII) Cl adsorption causes a semiconducting to metallic/semi-metallic transition which makes it suitable for application as an electroactive material. To elucidate this application, we investigated the change in binding energy (Eb), specific capacity, and open-circuit voltage as a function of the density of adsorbed Cl. The theoretical storage capacity of the chlorinated phosphorene is found to be 168.19 mA h g-1with a large average voltage (similar to 2.08 V) which is ideal number as a cathode in chloride-ion batteries.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: 4Citation - Scopus: 4Photonic Crystal Textiles for Heat Insulation(American Institute of Physics, 2023) Çetin, Zebih; Tunçtürk, Yiğit; Sözüer, Hüseyin SamiIn this work, we have studied transmission properties of a photonic crystal-like structure that can be woven into fabrics. An interesting possibility emerges when considering the potential energy savings through suppression of radiation. It is a well-established fact that every object at a finite temperature inherently emits electromagnetic waves. Within the specific context of the human body, radiation takes on a crucial role as a fundamental mechanism governing heat dissipation. Thus, exploring ways to manage or mitigate this radiation could offer innovative approaches to optimize energy consumption and enhance heat regulation. It is well known that a photonic crystal can block electromagnetic energy with a specific frequency that is falling into a photonic bandgap. By using the numerical method called a finite-difference time domain, we have shown that this property of a periodic structure can be used to make textiles to save energy that is used to heat a human body environment. Numerical calculations have shown that by using the proposed photonic crystal structure, 53 % of electromagnetic energy is reflected. Although we mainly focused on textiles, it is worth highlighting that the same fundamental principle can be extended to diverse fields; for example, this structure can be integrated with construction materials and effectively function as a radiation heat insulator. © 2023 Author(s).Article Anisotropic Tunability of Vibrational Modes in Black Phosphorus Under Uniaxial Compressive/Tensile Strain(Wiley, 2023) Li, Hao; Kutlu, Tayfun; Carrascoso, Felix; Şahin, Hasan; Munuera, Carmen; Castellanos Gomez, AndresStrain engineering is a powerful strategy for tuning the optical, electrical, vibrational properties of 2D nanomaterials. In this work, a four-point bending apparatus is constructed to apply both compressive and tensile strain on 2D anisotropic black phosphorus flake. Further polarized Raman spectroscopy is used to study the vibrational modes of black phosphorus flakes under uniaxial strain applied along various crystalline orientations. Here, a strong anisotropic blue/redshift of A1g, B2g, and A2g modes is found under compressive/tensile strain, respectively. Interestingly, mode A1g exhibits the maximum/minimum shift while mode B2g and mode A2g present the minimum/maximum shift when the strain is applied along armchair/zigzag direction. Density functional theory calculations are carried out to investigate the anisotropic strain response mechanism, finding that the strain-induced regulation of the PP bond angle, bond length, and especially interlayer interaction has a giant influence on the Raman shift. A four-point bending apparatus is constructed to study the effect of uniaxial strain on the vibrational property of anisotropic black phosphorus. Particularly, strong anisotropy on the Raman blueshift/redshift rate upon compressive/tensile strain can be observed, which results from the strain-induced regulation of the bond angle, bond length, and interlayer interactions according to density functional theory calculation analysis.imageArticle 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: 9Citation - Scopus: 9High Voltage Response of Graphene/4h-sic Uv Photodetector With Low Level Detection(Elsevier, 2023) Jehad, Ala K.; Ünverdi, Özhan; Çelebi, CemA self-powered graphene/silicon carbide (G/4H-SiC) ultraviolet photodetector of a p-i-n like-structure with high voltage response has been fabricated to detect and measure low intensity ultraviolet (UV) radiation. Bilayer graphene sheet grown by chemical vapor deposition (CVD) method was transferred on the top of an epilayer structure of n-/n+ 4 H-SiC. In this structure, two Schottky contacts were formed: one at G/ n- 4H-SiC interface and the other at bulk-4 H-SiC/Cr/Au interface. The photodetector's characteristic measurements revealed low dark current of - 0.58 nA and spectral voltage responsivity of - 0.75 V/W at 300 nm wavelength. Under low level UV illumination of 300 nm wavelength, the photodetector exhibited a leakage current and a photogenerated response voltage of 1.1 nA and 10 mV, respectively. The time-dependent photovoltage measurements displayed a rapid photovoltage response with rise and decay times of -74 ns and - 580 ns, respectively. This novel device holds promise for applications requiring sensitive and self-powered UV detection.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 Citation - WoS: 3Citation - Scopus: 3Amperometric Detection of Nh3 by Aromatic Sam-Modified Graphene(IEEE, 2023) Yağmurcukardeş, Nesli; Bayram, Abdullah; Aydın, Hasan; Can, Mustafa; Demiç, Şerafettin; Açıkbaş, Yaşar; Çelebi, CemAmmonia (NH3) is a toxic substance resulting in various acute and chronic effects on individuals. NH3 detection, monitoring methods, and detection tools are desperately needed. In this work, we improved the NH3 sensing capabilities of grapheme (GP) films deposited by chemical vapor deposition (CVD) by modifying aromatic self-assembled monolayer (SAM) molecules such as 5-[(3-methylphenyl) (phenyl) amino] isophthalic acid (MeIPA) and 5-(diphenyl)amino] isophthalic acid (PhIPA) on amperometric detection method. Morphological investigations of the films were carried out by optical and scanning electron microscopy (SEM). Surface potential was characterized with Kelvin probe force microscopy (KPFM), and vibrational properties were characterized with Raman spectroscopy. MeIPA modification increased NH3 uptake by two times compared to unmodified GP. The results indicated that the SAM modification enhanced NH3 molecule adsorption and improved its periodic reversible and reproducible response using the amperometric detection system, indicating that SAM molecules might be a feasible probe for NH3. © 2001-2012 IEEE.