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 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 Citation - WoS: 1Citation - Scopus: 1Biophysical Assessment of Protein Stability in Ethanol-Stressed Environments via UV Absorption and Fluorescence Spectroscopies(Elsevier, 2026) Akyuz, Ersed; Vorob'ev, Mikhail M.; Guler, GunnurMaintaining the structure and functionality of proteins is crucial in applications ranging from food preservation to pharmaceutical formulation. Ethanol, while commonly used as a solvent and preservative, can induce structural changes in proteins depending on its concentration and the specific structure of the protein itself. This study investigates the structural effects of ethanol on three types of model proteins, namely bovine serum albumin (BSA), beta-Lactoglobulin (beta-Lg), and beta-Casein (beta-Cn), by using UV-Vis spectroscopy and fluorescence spectroscopy. The conformational responses of proteins in water-EtOH solutions of various ethanol concentrations (0-10 %, v/v) were analyzed through absorbance and emission spectral changes. At increasing ethanol concentration, UV absorption data showed distinct protein-dependent spectral changes. beta-Lg and beta-Cn exhibited strong hypochromism (an absorbance decrease of similar to 25 %) and red-shifting at 222 nm and 220 nm, respectively, indicating partial unfolding and solvent exposure of aromatic residues. BSA demonstrated subtle changes, and consistent quenching in fluorescence with a continuous blue-shifting to 330 nm, suggesting a moderate overall stability and local rearrangements in its structure. beta-Cn exhibited red-shifted fluorescence and quenching, reflecting its flexible, disordered structure and heterogeneous response to solvent conditions. Statistical analysis revealed that while fluorescence spectroscopy was highly sensitive to the intrinsic differences between proteins (p < 0.001), the ethanol-induced conformational changes were too subtle to be detected as a statistically significant treatment effect. The consistency of these trends indicates a rational underlying mechanism of interaction. This reflects the subtle nature of the effect at the tested concentrations rather than the absence of an effect. Moreover, these results unveil the protein-specific effects of ethanol and strongly emphasize the importance of solvent composition in maintaining protein integrity. Ethanol concentrations up to 5 % may offer protein stability whereas high ethanol levels (>= 5-10 %) promote structural perturbations. These results will be useful for both basic scientific research, such as biophysical studies and the advancement of optical techniques, and various industrial uses.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 Optimization of Extraction for Antioxidant and Photoprotective Bioactive Compounds From Ulva Rigida(Elsevier, 2025) Toy, Elif; Bicakci, Beyza Tutku; Erdem, Cansu; Sincar, Bahar; Ozdemir, Feyza; Keskin, Melike; Bayraktar, OguzThis study presents the development and optimization of a green extraction bioprocess for Ulva rigida, aiming to efficiently recover bioactive compounds with antioxidant and photoprotective properties using response surface methodology (RSM). A Box-Behnken design evaluated the combined effects of ethanol concentration (0-100 %), solid-to-liquid ratio (20-40 mL g-1), and extraction time (8-24 h) on extraction yield, antioxidant capacity, and sun protection factor (SPF). All variables significantly impacted extract quality, with ethanol concentration being the most influential. Optimal conditions (100 % ethanol, 1:20 ratio, 16 h) yielded an extract with SPF 11.61 and antioxidant activity of 16.91 mg Trolox/g. Preparative thin-layer chromatography (TLC) of the optimized extract produced three bioactive fractions exhibiting up to 2.3-fold higher SPF and 5-fold greater antioxidant activity. Liquid chromatography-mass spectrometry (LC-MS) analysis confirmed selective enrichment of carotenoids and polyphenols. These findings demonstrate the value of statistically optimized, bioactivity-guided extraction in enhancing Ulva-derived ingredients for cosmeceutical use.Editorial Editorial on: 22nd International Symposium on Boron, Borides and Related Materials (ISBB 2024)(Elsevier, 2025) Balci-Cagiran, Ozge; Yucel, Onuralp; Somer, MehmetArticle The Johnson and Cook Damage and Flow Stress Model Parameters of a Rolled Stainless Steel 304 Alloy(Elsevier, 2026) Akdogan, Ibrahim Berk; Davut, Kemal; Gueden, Mustafa; Erten, Hacer Irem; Tasdemirci, Alper; Maleki, Farshid Khosravi; Gok, Mustafa SabriPrevious studies on stainless steel 304 alloy (SS 304) have mostly focused on the stress-strain behavior as function of the volume fraction of deformation induced martensite and the applied strain and strain rate. Although equally important, the failure/fracture of this alloy has not been thoroughly investigated so far. In the present study, the Johnson and Cook (JC) damage model parameters of a rolled-SS 304 alloy, valid at a high strain rate (2900 s-1), were experimentally determined and numerically validated along with the JC flow stress parameters. The tensile failure strain of the alloy decreased as the strain rate increased from 10-3 to 10-1 s-1 and to 2900 s-1. Experimentally lower flow stresses at 2900 s-1 than at 1x10-3 s-1 were also found at the strains above 0.2, which was attributed to the adiabatic heating that declined the extend of the martensitic transformation at increasing strains. The determined damage and flow stress model parameters were further calibrated with the results of the numerical models of the quasi-static and high strain rate tension tests. Microscopic analyses and the hardness measurements on the untested and tested specimens confirmed the martensitic transformation and the highest hardness values were found in the specimens tested at 1x10-3 s-1. The martensite volume fraction as function strain rate until about necking strain (homogeneous deformation) was calculated and also microscopically determined using the electron back-scatter diffraction (EBSD) for the specimens tested at different strain rates. The results indicated the highest martensite volume fraction in the specimens tested at 10-3 s-1 (0.55-0.6) and the lowest in the specimens tested at the high strain rate (0.27-0.30). An agreement between the calculated and the EBSD determined martensite volume fractions was shown for the studied alloy.Article Citation - Scopus: 1Adulteration of Pomegranate Molasses With Sugar Syrups: Application of FTIR-ATR Spectroscopy and Chemometrics(Elsevier, 2025) Kilinc, Gizem Simge; Uncu, Oguz; Eren, Ismail; Bagdatlioglu, NerimanIn this study, it was aimed to determine the adulteration ratio of pomegranate molasses (PM) with sugar syrups by using FTIR spectroscopy based upon chemometrics. With this intention, 34 pure PM samples were supplied from local manufacturers and adulterated with high fructose corn syrup (HFCS), glucose-fructose syrup (GFS) and beet sugar syrup (BSS) in varying ratios (5-50 %, w/w). Authentic and adulterated PM samples were analyzed in the range of 4000 and 400 cm(-1) wavenumber by FTIR spectroscopy. PCA was applied as a pretreatment for classification and regression analysis to select the spectral region and data reduction. Whereby the DD-SIMCA models were created using this information. The adulterated and authentic samples were classified correctly by the developed DD-SIMCA models. In the calibration and prediction model of DD-SIMCA, authentic and adulterated PM samples were correctly classified with high sensitivity (>= 0.91) and specificity (>= 0.94), and a clear distinction was observed with high efficiency (>= 0.94). Adulteration rates in PM samples were determined by PLS-R analysis. The correlation coefficients (R-2 >= 0.98) of models were also found quite high. As a consequence, FTIR spectroscopy in conjunction with chemometric approaches could be applied as a quick, dependable, non-destructive, and environmentally friendly tool for categorizing, distinguishing, and quantifying adulteration rates in PM samples.Article Functional Manipulation of Nonspherical Nanoparticles With Cascaded Reconfigurable Modules(Elsevier, 2025) Arslanyurek, Seyma; Dinleyici, Mehmet SalihSelective nanoparticle sorting is essential for applications requiring monodisperse distributions, yet conventional methods lack adaptability for shape-based separation. This study introduces a reconfigurable optical manipulation technique that dynamically sorts spherical and non-spherical nanoparticles using cascaded modules based on evanescent fields. Optical forces were calculated using the Discrete Dipole Approximation (DDA) method, enabling the modeling of various particle shapes and accurately capturing rotational and translational movements. Two cascaded strategies are proposed: the first approach enables fluid-assisted filtration by selectively trapping spherical particles while allowing non-spherical ones to be carried away by the flow. The second strategy first induces the rotational alignment of particles and then employs a trapping mechanism that selectively retains specific geometries, enabling the separation of spherical and non-spherical nanoparticles. Unlike traditional approaches, this method enables high-precision, shape-selective separation without external flow modifications. The results demonstrate unprecedented control and efficiency in nanoparticle sorting, offering a scalable, high-throughput solution for microfluidic and optofluidic applications.