WoS İndeksli Yayınlar Koleksiyonu
Permanent URI for this collectionhttps://hdl.handle.net/20.500.12573/394
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Article Depositional Model, Cyclicity, and Hydrocarbon Potential of the Eocene Sakesar Carbonate Ramp, Salt Range, Pakistan(Springer, 2026-02-02) Shah, Syed Bilawal Ali; Shah, Syed Haider AliThe Sakesar Formation in the Salt Range, Pakistan, represents a well-developed Eocene carbonate ramp deposited along the southern Tethyan margin. This study integrates petrographic analysis, palynofacies evaluation, organic geochemical measurements and sequence stratigraphic interpretation to characterise the depositional environments, diagenetic evolution, and petroleum system potential of the formation. Six microfacies (MF1-MF6) were identified through thin-section petrography ranging from high-energy shoal grainstones to low-energy lagoonal marls. Quantitative palynofacies analysis shows energy dependent trends in organic matter composition, with shoal facies dominated by opaque phytoclasts and lagoonal facies enriched in amorphous organic matter (AOM). Organic geochemical measurements including Total Organic Carbon (TOC), Hydrogen Index (HI), Oxygen Index (OI), and Rock-Eval pyrolysis parameters, combined with vitrinite reflectance (Ro) data, indicate that lagoonal marl-micrite facies (MF6) contain Type II kerogen with the highest TOC values (2.80%), elevated HI (293 mg hydrocarbons per gram TOC), and peak oil-window maturity (0.72% Ro). These attributes identify MF6 as the primary oil-prone source rock. Mid-ramp wackestones and packstones (MF3-MF4) possess moderate generative potential and serve as internal seals or baffles, whereas high-energy shoal facies (MF1-MF2) show favourable reservoir characteristics but limited source potential. Sequence-stratigraphic analysis demonstrates that maximum flooding surfaces (MFS) frequently coincide with organic-rich MF6 intervals, producing predictable vertical stacking of source, seal, and reservoir units at parasequence scale. The integrated petrographic, palynofacies, and geochemical framework confirms the dual role of the Sakesar Formation as both a reservoir and a source-seal interval, with metre-scale cyclicity enhancing hydrocarbon charge and trapping efficiency. These findings refine the depositional and petroleum system model of the Sakesar carbonate ramp and provide valuable predictive analogues for Eocene carbonate exploration within the Himalayan foreland basin and related Tethyan settings.Article Enhanced Photoluminescence and Stability of CsPbBr3 Perovskite Nanocrystals Through AuCl Doping(Springer, 2026-02) Khorasani, Azam; Mutlugun, EvrenThis study delves into the transformative effects of inorganic gold chloride (AuCl) doping on all-inorganic cesium lead bromide (CsPbBr3) colloidal perovskite quantum dots (PeQDs). Using a precise hot injection synthesis method, AuCl was introduced at concentrations ranging from 0 to 10%, enabling a comprehensive analysis of its impact on the structural, morphological, and optical characteristics of CsPbBr3 PeQDs. We systematically investigated how varying AuCl levels influence photoluminescence (PL), PL quantum yield (PLQY), and the stability of these quantum dots. Advanced characterization techniques, including X-ray diffraction (XRD), scanning transmission electron microscopy (STEM), energy dispersive X-ray analysis (EDX), Fourier-transform infrared spectroscopy (FTIR), UV-Vis absorption, steady-state PL, absolute PL measurement, and time-resolved PL (TRPL), provided a detailed insight into these changes. Our findings indicate that AuCl doping is successfully integrated into CsPbBr3 PeQDs, with 5% identified as the optimal concentration. At this level, the quantum dots show enhanced PLQY, superior crystallinity, and increased stability at 50 degrees C and in ethanol solvent compared to undoped samples. While higher doping levels reduce QY and PL slightly, they still outperform the undoped CsPbBr3 PeQDs. These results demonstrate that AuCl doping can fine-tune the structural and optical properties of CsPbBr3 PeQDs, marking a significant step forward in developing tailored materials for advanced optoelectronic applications.Article Citation - WoS: 1Citation - Scopus: 2Green Synthesis and Characterization of Zinc Oxide Nanoparticles via Thyme for Biomedical Applications: Effect of Plant Extract Concentration and Drying Method(Springer, 2025-10-15) Karakaya, Humeyra; Kizilates, Burcu; Erdem, IlkerGreen synthesis of nano particles using plant extracts is sustainable, cost-effective, and eco-friendly. However, the synthesis parameters are still being investigated. In this study, zinc oxide nanoparticles (ZnO NPs) were prepared via thyme extract (green synthesis) and the effect of synthesis parameters were investigated. Samples with different concentrations of thyme plant extract (PE) (10, 16 & 24% (v/v) PE / Zn salt solution) were prepared and two different drying methods (freeze-drying (FD) and oven-drying (OD)) were performed. XRD results showed the hexagonal crystalline ZnO were formed with considerable crystallinity (70.8-75.1%) without further heat treatment (calcination). The crystallite sizes of ZnO NPs were determined to be in the range of 11.9-14.8 nm. The ZnO NPs prepared via PE concentration of 16% (v/v) and freeze-drying was with the finest crystallite size (11.9 nm) and considerable crystallinity (72.9%). ZnO NPs prepared via FD method were found to have smaller particle sizes, thus providing a higher surface-to-volume ratio. DLS (dynamic light scattering) analysis was used for determining the particle size distribution (PSD) and surface charge of ZnO NPs at acidic, neutral and basic pH values. The antibacterial characteristics of ZnO NPs were determined against Gram (+) and (-) bacteria. The ZnO NPs with the finest microstructure (16% PE (v/v), FD) had the highest antibacterial activity. The green synthesized ZnO NPs prepared in this study may be promising candidates for various applications including biomaterials and biomedical applications with their fine microstructure and considerable antibacterial activity.Article Enhanced Photoluminescence via Plasmonic Gold Nanoparticles and Improved Stability of Perovskite Nanocrystals in Macroporous (Polydimethylsiloxane) PDMS Matrices(Springer, 2025-10-09) Ocal, Sema Karabel; Tiras, Kevser Sahin; Onses, M. Serdar; Mutlugun, EvrenIn this work, we report a simple and cost-effective method for improving both the environmental stability and photoluminescence quantum efficiency (PLQY) of perovskite nanocrystals (PNCs). Through their embedding in a specially designed macroporous polydimethylsiloxane (MPDMS) matrix and incorporation of plasmonic gold nanoparticles (Au NPs), remarkable improvements are achieved. The resulting MPDMS@PNC composites are seen to retain near-unity quantum efficiency even after 24-h immersion in water and are observed to retain over 85% of the original efficiency even at 75 degrees C, displaying excellent thermal stability. More interestingly, by incorporating Au NPs and subjecting the material to mechanical pressure, the lifetime of the PNCs gets further increased. This is due to the more intimate spatial arrangement of Au NPs in the porous matrix, enhancing localized surface plasmon resonance (LSPR) coupling and thereby enhancing the photoluminescence (PL) of the PNCs. In general, this approach offers a scalable and robust route to designing stable, high-performance perovskite-based materials for next-generation optoelectronic applications.Article Citation - WoS: 4Citation - Scopus: 4Thermal Conductivity and Interfacial Energy of Solid Bi in the Bi-Ag Eutectic System(Springer, 2015-05-15) Altintas, Yemliha; Ozturk, Esra; Aksoz, Sezen; Keslioglu, Kazim; Marasli, Necmettin; Maraşlı, Necmettin; Keşlioğlu, Kâzım; Altıntas, YemlihaThe equilibrated grain boundary groove shapes for solid Bi (Bi-2.87 at.%Ag) in equilibrium with Bi-Ag eutectic liquid have been observed from quenched sample with a radial heat flow apparatus. The Gibbs-Thomson coefficient, solid-liquid interfacial energy and grain boundary energy of solid Bi have been determined from the observed grain boundary groove shapes. The variation of thermal conductivity with temperature for eutectic solid phase (Bi-4.7 at.%Ag) has been measured. The ratio of thermal conductivity of equilibrated eutectic liquid phase to eutectic solid phase has also been measured with a Bridgman-type growth apparatus at the melting temperature. The Gibbs-Thomson coefficient, solid-liquid interfacial energy and grain boundary energy of solid Bi in equilibrium with Bi-Ag eutectic liquid were determined to be (9.2 +/- A 0.6) x 10(-8) K m, (52.7 +/- A 6.3) x 10(-3) J m(-2) and (102.4 +/- A 13.3) x 10(-3) J m(-2), respectively, from observed grain boundary groove shapes.Article Citation - WoS: 1Citation - Scopus: 1The Variations of Electrical Resistivity and Thermal Conductivity With Growth Rate for the Zn-Al Eutectic Alloy(Springer, 2021-06-24) Marasli, Necmettin; Bayram, Umit; Aksoz, SezenThe Zn-Al-Cu alloy (Zn-5wt%Al-0.5wt%Cu) is solidified with different growth rates (V = 8.45-2087.15 mu m s(-1)) at a constant temperature gradient (G = 3.67 K mm(-1)) using Bridgman-type directional solidification apparatus (BTDSA). The thermal conductivity (K) and electrical resistivity (rho) for the Zn-Al-Cu alloy solidified with the different V values are measured by the longitudinal heat flow method (LHFM) and DC four-point probe technique (FPPT), respectively. The lambda and K decrease with the increasing V, while the q increases with increasing V in the Zn-Al-Cu eutectic alloy. The dependences of rho and K on lambda and V for the Zn-Al-Cu eutectic alloy are obtained as rho = 9.98 x 10(-8)lambda(-0.18), q = 7.03 x 10(-8) V-0.07, K = 110.91 lambda(0.104) and K = 144.59V(-0.040), respectively. The melting enthalpy (DHf) and specific heat difference between solid and liquid phases (Delta C-p) for the Zn-Al-Cu eutectic alloy are determined as 113.89 J g(-1) and 0.172 J g(-1) K-1, respectively, by the differential scanning calorimetry (DSC).Article Citation - WoS: 1Citation - Scopus: 1The Experimental Determination of Interfacial Energies for Solid Zn in Equilibrium With Zn-Al Liquid(Springer, 2015-06-16) Altintas, Yemliha; Ozturk, Esra; Aksoz, Sezen; Keslioglu, Kazim; Marasli, NecmettinThe equilibrated grain boundary groove shapes of solid Zn in equilibrium with Zn-Al-Sb liquid were observed from a quenched sample using a radial heat flow apparatus. The Gibbs-Thomson coefficient, solid-liquid interfacial energy, and grain boundary energy of the solid Zn were determined from the observed grain boundary groove shapes. The thermal conductivity of the eutectic solid phase for Zn-0.4 at. pct Al-0.4 at. pct Sb alloy and the thermal conductivity ratio of the liquid phase to the solid phase for Zn-0.4 at. pct Al-0.4 at. pct Sb alloy at eutectic temperature were also measured with a radial heat flow apparatus and a Bridgman-type growth apparatus, respectively.Article Citation - WoS: 14Citation - Scopus: 14Synthesis of Polyketone-G Styrene Sulfonate Cation Exchange Membrane via Irradiation and Its Desalination Properties(Springer, 2017-11) Kim, In Sik; Hwang, Chi Won; Kim, Young Joong; Canlier, Ali; Jeong, Kyung Seok; Hwang, Taek SungUsing the radiation grafting technique, polyketone membranes were graft copolymerized with sodium styrene sulfonate (SSS) in the presence of additives such as Mohr's salt and H2SO4. Fourier-transform infrared (FT-IR) spectroscopy was used to characterize the grafted membranes. Water uptake (WU), ion exchange capacity (IEC) and electrical resistance (ER) of the prepared membranes were measured in order to evaluate their physical properties The prepared membranes were applied to the membrane capacitive deionization (MCDI) process, in which their salt removal rates were evaluated and compared to those of CDI (capacitive deionization) process. The degree of grafting rose from 14.4% to 81.4% as the irradiation dose and the monomer concentration were increased. The water uptake ranged from 7.9% to 34.2%. The ionexchange capacity was observed between 0.43 meq/g and 1.1 meq/g, and the electrical resistance had values ranging from 12.2 Omega center dot cm(2) to 2.1 Omega center dot cm(2). The electrical resistance decreased as the ion-exchange capacity was extended. When the prepared cation exchange membrane was used in the MCDI process, the salt removal rate reached 87.6%, which was much higher than 28.8% of CDI process.Article Citation - WoS: 3Citation - Scopus: 3Stoichiometric Amorphous Boron Carbide (BC)(Springer, 2020-07-17) Yildiz, Tevhide Ayca; Durandurdu, MuratIn this work, a stoichiometric amorphous boron carbide (a-BC) network is constructed via an ab initio molecular dynamics approach. Its structural, electrical and mechanical features are reconnoitered in details and compared with those of turbostratic BC and some important graphite-like amorphous materials. Our computer-generated structure exhibits strong chemical disorder as seen in turbostratic BC. However, it has mixed sp(2) and sp(3) hybridizations and the average coordination number of B and C atoms is projected to be similar to 3.22 and 3.46, correspondingly. Consequently, a-BC appears to be structurally different from turbostratic BC and graphite-like amorphous systems. a-BC is semiconductor having a theoretical band gap of similar to 0.20 eV. The bulk, Young's and shear moduli are estimated as similar to 105, 142 and 56 GPa, respectively. Its Vickers hardness is calculated to be about 7-8.5 GPa. a-BC is anticipated to be electronically and mechanically parallel to amorphous boron carbonitride.Article Square Root Computation in Finite Fields(Springer, 2024-03-12) Adiguzel-Goktas, Ebru; Ozdemir, EnverIn this paper, we present a review of three widely-used practical square root algorithms. We then describe a unifying framework where each of these well-known algorithms can be seen as a special case of it. The framework with singular curves offers a broad perspective to compare and further improve the existing methods in addition to offering a new avenue for square root computation algorithms in finite fields.