Scopus İndeksli Yayınlar Koleksiyonu / Scopus Indexed Publications Collection
Permanent URI for this collectionhttps://hdl.handle.net/11147/7148
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Article Robust Scheduling of Crude Oil Farming and Processing Under Uncertainty(Elsevier, 2026) Yalcin, Damla; Sildir, HasanThe sulphur content in crude oil has a significant impact on refinery operations, influencing the feasibility of crude blending, the distribution of product yields, and overall economic performance. Variations in sulphur content introduce uncertainty in the short-term scheduling of crude oil loading, blending, and distillation processes. This study introduces a scenario-based stochastic optimization framework in which sulphur uncertainty is treated as a central modeling element, represented through a regression-based relationship with specific gravity (SG). The approach systematically propagates uncertainty through blending decisions, crude distillation unit (CDU) feed composition, and product yields. The problem is modeled as a mixed-integer quadratically constrained programming (MIQCP) formulation within a continuous-time scheduling framework, enabling the simultaneous optimization of timing, blending, and processing strategies. The results indicate that increased sulphur uncertainty adversely affects the distribution of yields for nine end-products, resulting in profit losses. These findings underscore the importance of explicitly managing compositional uncertainty and provide insights into cost-performance trade-offs in refinery scheduling.Article Rice-Like, Hollow, and Rhombohedral Nano-Calcite Synthesis by Carbonization(Elsevier, 2026) Kilic, Sevgi; Toprak, Gorkem; Ozdemir, EkremControlling the morphology and size of calcium carbonate (CaCO3) remains an essential challenge in the production of high-performance fillers and advanced functional materials. Here, we report a continuous carbonization strategy that enables the synthesis of monodisperse nano-calcite particles with tunable rice-like, hollow, and rhombohedral morphologies through precise control of CO2 dissolution into a flowing Ca(OH)2 solution under diffusion-limited conditions. A two-stage reactor was designed to decouple nucleation and growth by separating the gas-liquid interaction zone from a stabilization tank. pH and conductivity analyses revealed that crystallization is primarily governed by the CO2 dissolution kinetics rather than mixing intensity in the stabilization tank. SEM and XRD analyses demonstrate a distinct crystallization sequence such that initial formation of rice-like calcite, subsequent development of hollow nanoparticles through selective tip dissolution, and final transformation into rhombohedral calcite via dissolution-reprecipitation mechanism. The method provides a reproducible, template-free route for fabricating hollow CaCO3 nanoparticles, overcoming limitations of bubbletemplating and additive-mediated techniques. This scalable process provides a robust foundation for producing high-surface-area CaCO3 nanomaterials which have potential applications in thin films, ceramics, protective coatings, lightweight composites, thermal/acoustic insulation, adsorption, and catalysis, where tailored particle morphology and size can significantly enhance performance.Article Hydrological Insights From SWOT: Comparative Analysis of Water Surface Elevation and Area Time Series From Hydrocron API(Elsevier, 2025) Karahan, Sait Mutlu; Gunduz, OrhanThe Surface Water and Ocean Topography (SWOT) mission plays an essential role in enhancing the monitoring and management of inland water bodies by providing high-resolution global observations of surface water dynamics. A critical tool in leveraging SWOT data is the Hydrocron API (Application Programming Interface), which facilitates access to temporally consistent SWOT-derived hydrological datasets. In this study, SWOT's Lake data "L2_HR_LakeSP" time series data retrieved from Hydrocron was utilized to evaluate water surface elevation (WSE) and surface area dynamics across six distinct lake locations around the world. To quantify the accuracy of SWOT, error metrics including Symmetric Mean Absolute Percentage Error (SMAPE), Absolute Percentage Error (APE), and Normalized Root Mean Square Error as a percentage (NRMSE%) were computed for both WSE and surface area estimates. The results indicated that the highest WSE error, with a SMAPE of 3.83 %, was observed in the lake characterized by the smallest surface area, suggesting a sensitivity of SWOT measurements to spatial scale. Conversely, the greatest error in surface area estimation occurred in the shallowest lake with SMAPE and APE values of 19.56 % and 22.01 %, respectively, highlighting the influence of bathymetric complexity on SWOT's detection capabilities. Despite these localized variances, the overall performance of SWOT data was found to be highly promising, demonstrating strong potential for operational hydrological applications and long-term water resource monitoring. The integration of SWOT observations with hydrological models via platforms such as Hydrocron underscores the mission's potential in advancing the understanding of inland water dynamics at both regional and global scales.Article Magnetic Levitation-Based Determination of Single-Nuclei Density(Elsevier, 2026) Anil-Inevi, Muge; Sarigil, Oyku; Unal, Yagmur Ceren; Tekin, H. Cumhur; Mese, Gulistan; Ozcivici, EnginThe biophysical properties of cells and intracellular compartments provide critical insights into their structural and functional states, holding significant potential for biological and medical applications. Single-cell density has recently emerged as a promising biomarker in various research areas, including disease detection, making its precise measurement in biological samples an important analytical objective. Magnetic levitation offers significant advantages over traditional density detection techniques by enabling single-cell analysis rather than bulk measurements, providing precise quantification while preserving natural sample properties and eliminating the need for complex and expensive equipment. While magnetic levitation has been successfully applied to singlecell and cell-aggregate analysis, its use for subcellular compartments remains unexplored. Here, we demonstrate the first application of magnetic levitation technology for the density-based analysis of cell nuclei, a critical organelle essential for genomic preservation and organization. To accommodate the unique size and density characteristics of nuclei compared to whole cells, we systematically investigated appropriate paramagnetic agents, sample loading concentrations, and nuclear equilibrium times required for optimal levitation. We mapped density distributions of nuclei from different cell lines and conducted parallel assessments of cellular and nuclear density changes following cell cycle perturbations and treatments inducing cell death through distinct mechanisms. Our findings establish magnetic levitation as a powerful tool for subcellular density analysis, with potential applications in cell biology research and clinical diagnostics through improved understanding of subcellular physical parameters.Article Design, Synthesis, and Evaluation of Anticancer Activities of 1,2-Diborolane Derivatives for Hepatocellular Carcinoma: an in Vitro and in Silico Study(Elsevier, 2026) Sahin, Yuksel; Antika, Gizem; Aktan, Cagdas; Metin, Kubilay; Ozgener, HuseyinHepatocellular carcinoma (HCC) is the most prevalent form of primary liver cancer and remains a major global health challenge due to limited treatment options and poor prognosis. Boron-containing compounds have garnered attention for their diverse biological activities, including pro-apoptotic effects in various types of cancer. In this study, we synthesized a panel of novel 1,2-N-substituted-1,2-diborolane derivatives and evaluated their antiproliferative, antimigratory, and apoptotic effects on hepatocellular carcinoma cell lines, HepG2 and Hep3B. Spectroscopic analyses confirmed the structural integrity of the synthesized compounds, revealing characteristic 1H-, 11B-, and 13C-NMR shifts consistent with boron-oxygen and boron-nitrogen bonding patterns. The derivatives, particularly compounds 2, 3, and 6, demonstrated potent and selective cytotoxicity toward HCC cells, with compound 3 exhibiting the lowest IC50 value (6.75 mu M) in HepG2 cells. Their time-dependent anti-proliferative effects were further supported by colony formation assays demonstrating long-term growth suppression, while wound healing assays revealed marked inhibition of HepG2 cell migration, indicating the compound's anti-metastatic potential. Our results demonstrate that the compound significantly induces apoptosis, modulates the expression of key apoptotic genes (Bax, Bcl-2, and caspase-3). In silico molecular docking further confirmed strong binding affinity to the anti-apoptotic Bcl-2 protein, supporting the proposed mechanism of action. These findings highlight the compound as a promising candidate for further preclinical evaluation in liver cancer therapy.Article A Novel ORC-PEM Integrated System for Sustainable Hydrogen Production from Low-Grade Waste Heat in Oil Refineries(Elsevier, 2025) Nazerifard, Reza; Mohammadpourfard, Mousa; Zarghami, RezaThis study presents an integrated multi-generation system for sustainable hydrogen production by harnessing low-grade waste heat from the overhead stream of the NHT unit's stripper column in an oil refinery. The proposed system integrates an ORC with a PEM electrolyzer, forming a novel energy solution that efficiently converts waste heat into clean hydrogen through electricity generation. A detailed model of the proposed system is developed, enabling a comprehensive assessment of its performance from thermodynamic, economic, and environmental viewpoints. At the same time, key operational parameters are optimized using the RSM-BBD method to minimize the hydrogen production cost, thereby enhancing the system's economic viability and practical implementation. The results demonstrated that the system achieves a yearly hydrogen production of 304.53 tons under optimized conditions, for 2.36 $/kg. The integrated system's overall energy and exergy efficiencies are calculated at 8.62 % and 33.43 %, respectively, demonstrating its high thermodynamic performance. Additionally, the system mitigates 3047 tons of CO2 annually by displacing conventional hydrogen production methods.Article Molecular Dynamics Study on the Coupled Effects of Size and Pre-Existing Oxide Layer on the Compressive Mechanical Properties of Copper Nanowires(Elsevier, 2026) Aral, Gurcan; Islam, Md Mahbubul; Amodeo, JonathanCopper nanowires generally exhibit a native oxide shell layer, which can significantly impact their performance and reliability, especially in nanoelectronics applications. Using molecular dynamics simulations with the variable charge ReaxFF potential, we systematically examine the effects of pre-existing oxide layers on the mechanical properties and deformation mechanisms of [001]-oriented Cu nanowires with varying diameters at room temperature. Our findings reveal a size-dependent influence of the native oxide layer on the mechanical behavior. Specifically, the formation of an oxide shell (CuxOy) around the Cu core reduces the activation barrier for defect nucleation, reducing yield properties and, thereby, weakening the nanowires. This effect is more pronounced in smaller samples due to the intensified interaction between the metallic core and the oxide shell. Additionally, while the strength, elastic modulus, and yield stress increase with the diameter of pristine and oxidized specimens, pristine nanowires consistently exhibit superior mechanical properties when compared to their oxidized counterparts. The degradation in mechanical performance primarily stems from the early onset of plasticity initiated at the oxidized surface. These findings emphasize the detrimental impact of native oxide layers on the mechanical behavior of Cu nanowires and highlight the critical role played by size upon the mechanical properties of nano-oxidized metal samples. This work provides valuable insights into tailoring the mechanical properties of Cu nanowires, contributing to the optimization of their performance in both nanoelectronics and mechanical applications.Article Reversibility and Entropy in Bubbling Fluidized Beds: A Recurrence-Based Analysis(Elsevier, 2026) Zarghami, Reza; Mohammadpourfard, Mousa; Akkurt, Gulden GokcenNonlinear time series analysis techniques were applied to characterize bubbling fluidization. The delay method was used to reconstruct the state space attractor and analyze the reconstructed state space. The experiments were carried out in a laboratory-scale fluidized bed, operated under ambient conditions and with various sizes of particles, settled bed heights, measurement heights, and superficial gas velocities. The reversibility of the gas-solid fluidized bed hydrodynamics was investigated using pressure fluctuations by recurrence plot analysis. The anti-diagonal lines of the recurrence plot (RP) were regarded as a measure of reversibility. It was shown that the reversibility versus gas velocity has a concave shape in the bubbling regime. The highest reversibility occurs at velocities remarkably lower than the turbulent transition velocity. In addition, reversibility increases as the size of the particles increases. The Kolmogorov entropy was also estimated to confirm the reversibility analysis in the state space domain. In addition, the average cycle frequency and wideband energy in the frequency domain were also used to clarify the results in the state domain. It was found that a minimum in average cycle frequency, wideband energy, and entropy with an increase in the velocity corresponds to the transition between macro-structures and finer structures of the fluidization system. This minimum was primarily found in the macro-structures of the bubbling fluidization system. These findings can provide a practical tool for the optimal design and operation of the fluidized bed.Article Antidiabetic and Anticancer Properties of Sun-Dried Fig (Ficus Carica) Stalk Pectin: Effects on Intestinal Glucose Absorption and Colon Cancer Cell Growth(Elsevier, 2025) Baser, Filiz; Cavdaroglu, Elif; Yemenicioglu, Ahmet; Gulec, SukruThis study aims to characterize the physiological activity of fig stalk pectin (FSP) in terms of antidiabetic and anticancer activities. Also, the potency of FSP has been interpreted as a functional food ingredient in yogurt. The galacturonic acid content (65 %), degree of esterification (63 %), and enzymatic sugar analysis showed that FSP is a high methoxyl pectin rich in RG-I content (similar to 22 %). Anti-diabetic characteristics of FSP demonstrated that FSP inhibited 2-deoxyglucose uptake into CaCo-2 cells and reduced glucose absorption in the intestinal transport system after being added as an ingredient in yogurt at the concentration of 2 % (w/w). The antidiabetic activity of FSP was attributed to its capacity to modify the rheological properties of yogurt with a high-water binding capacity (10 g/g), and it increased the viscosity of digested yogurt samples considerably (from 89 to 110 Cp). Moreover, the characterization of anticancer properties showed that FSP inhibited the proliferation of colon cancer CaCo-2 cells by disturbing cell cycle progression, leading to S phase arrest, and showing apoptosis-inducing ability. Further research, including in vivo and clinical trials, is necessary to validate the observed health benefits of FSP.Article On the Construction of Xor-Magic Graphs(Elsevier, 2026) Batal, AhmetA simple connected graph of order 2nis defined as a xor-magic graph of power n if its vertices can be labeled with vectors from Fn2 in a one-to-one manner such that the sum of labels in each closed neighborhood set of vertices equals zero. In this paper, we introduce a method called the self-switching operation, which, when properly applied to an odd xor-magic graph of power n, generates a xor-magic graph of power n + 1. We demonstrate the existence of a proper self-switching operation for any given odd xor-magic graph and provide a characterization of the cut space of a connected graph in the process. We also observe that the Dyck graph can be obtained from the complete graph of order 4 by applying three successive self-switching operations. Additionally, we investigate various graph products, including Cartesian, tensor, strong, lexicographical, and modular products. We observe that these products allow us to generate xor-magic graphs by selecting appropriate factor graphs. Notably, we discover that a modular product of graphs is always a xor-magic graph when the orders of its factors are powers of 2 (except for 2 itself). In the process, we realize that the Clebsch graph is the modular product of the cycle graph and the empty graph, each of order 4. By combining the self-switching operation with the modular product, we establish the existence of k-regular xor-magic graphs of power n for all n >= 2 and for all k is an element of {3, 5, 7, ... , 2n-5}boolean OR{2n-1}. We also prove that there is no (2n-3)-regular xor-magic graph of power n. Lastly, we introduce two more methods to produce xor-magic graphs. One method utilizes Cayley graphs and the other utilizes linear algebra. (c) 2025 Elsevier B.V. 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