Welcome to the Koç University Institutional Academic Repository
The Koç University Institutional Academic Repository (KUHub Research) is a state-of-the-art academic repository that consolidates all academic outputs—such as articles, conference proceedings, theses, research data, and more—produced by the university since its establishment in 1993.
KUHub Research adheres to the principles of Open Access and FAIR (Findable, Accessible, Interoperable, Reusable), providing access to the bibliographic records, research data, and full texts of research outputs. Equipped with innovative features such as Author Profile pages and enhanced tools, KUHub Research aims to enhance the visibility of researchers both nationally and internationally. KUHub Research aims to preserve and maintain Koç University's valuable academic legacy for future generations while also serving the needs of today’s researchers.
For more information or inquiries please contact openaccess@ku.edu.tr
To learn how to deposit your publications in your KUHub Research profile, watch our video guide: “How to Deposit Publications into KUHub Research?”
Recent Submissions
A machine learning approach for marginal fulfillment cost estimation in last mile delivery
(Elsevier, 2025-07-01) Nalbant, Ali; Yıldız, Barış; Graduate School of Sciences and Engineering; Department of Industrial Engineering; GRADUATE SCHOOL OF SCIENCES AND ENGINEERING; College of Engineering
Determining marginal fulfillment costs (MFC) is crucial for effective decision-making in online grocery retail, a sector struggling with small profit margins and arduous service requirements of attended home deliveries. Paramount to improving operational efficiency, e-grocers need accurate real-time MFC estimations to optimize their service offers and prices for online customers. Traditional methods for estimating MFC are either too slow for online decision-making or inaccurate. This paper introduces a novel machine learning (ML) approach that provides fast and accurate MFC estimations with the help of carefully engineered features (predictors) that can capture complex routing dynamics. Experiments with real-world data demonstrate the superiority of the proposed approach over state-of-the-art MFC estimation methods. Our analysis of more than 2000 potential predictors, from which 20 are curated for practical applicability, reveals critical insights into the use of network-level, neighborhood-based, and node-level features in capturing complex VRP dynamics to develop ML-based approaches to address problems that arise in different transportation applications.
Polyurethane synthesis revisited: effect of solvent, stoichiometry, and temperature on the reaction of MDI with polyether glycols
(Elsevier, 2025-05-09) Yılgör, İskender; Yılgör, Emel; Yıldırım, Armen; Department of Chemistry; KUYTAM (Koç University Surface Science and Technology Center); Graduate School of Sciences and Engineering; College of Sciences; GRADUATE SCHOOL OF SCIENCES AND ENGINEERING; Graduate School of Sciences and Engineering; Research Center
Thermoplastic polyurethanes (TPU) are one of the most widely investigated polymeric systems due to their interesting structure-morphology-property behavior. They also find broad range of applications in various fields. Global TPU market is projected to grow about 7.3 % annually from $2.30 billion in 2021 to $3.80 billion in 2028. 4,4′-Diphenylmethane diisocyanate (MDI) is the most widely used diisocyanate for the preparation of TPUs both in academia and industry. When TPU synthesis is carried out in solution, a polar aprotic solvent is necessary to obtain high molecular weight polymers. Most preferred solvents for TPU synthesis are high boiling, polar, aprotic solvents, such as dimethylacetamide (DMAC), dimethylformamide (DMF), dimethyl sulfoxide (DMSO) and N-methyl pyrrolidone (NMP). When MDI is used as the diisocyanate, depending on the solvent used and reaction temperature, extensive side reactions may be observed, which consume excess diisocyanate and affect reaction stoichiometry. Side reactions also strongly influence TPU structure, topology, microphase morphology, and properties. In this study influence of the solvent, initial [NCO]/[OH] stoichiometry and reaction temperature on the rate of isocyanate consumption and kinetics of the reactions between MDI and poly(tetramethylene oxide) glycol (PTMO) were investigated. Catalytic effect of DMF even at reactions conducted at room temperature were observed, resulting in significant excess MDI consumption due to extensive side reactions. During prepolymer formation in [MDI]/[PTMO] = 2.0 system at 50 °C, side reactions were minimized or eliminated by using THF/DMF or toluene/DMF (90/10 by volume) solvent mixtures.
Simple and green process for silk fibroin production by water degumming
(American Chemical Society, 2025-01-05) Atay, İpek; Yağcı, Mustafa Barış; Sürme, Saliha; Kavaklı, İbrahim Halil; Yılgör, Emel; Yılgör, İskender; KUYTAM (Koç University Surface Science and Technology Center); Department of Chemistry; Department of Chemical and Biological Engineering; Department of Molecular Biology and Genetics; College of Sciences; College of Engineering; Research Center
Silk fibroin (SF), a natural polymer with very desirable physicochemical and biological properties, is an ideal material for crafting biocompatible scaffolds in tissue engineering. However, conventional methods for removing the sericin layer and dissolving SF often involve environmentally harmful reagents and processes, requiring extensive dialysis procedures to purify the fibers produced. Such processes may also damage the surface and bulk properties of the SF produced. Here, we report a simple, green water degumming method, in which almost complete sericin removal of 30% by weight is achieved in 6 h in boiling water. The SF produced is easily dissolved in formic acid/orthophosphoric acid (90/10, 85/15, and 70/30) mixtures, eliminating the need for salts like LiBr and CaCl2 followed by dialysis and freeze-drying, thus simplifying the process significantly. Additionally, our findings demonstrate significantly enhanced cell viability in electrospun poly(lactic acid)/SF blends. Overall, SF production via water degumming offers an eco-friendly pathway for generating bioactive scaffolds in tissue engineering applications.
Backward behavior and determining functionals for chevron pattern equations
(Elsevier, 2025) Kalantarov, Varga; Kalantarova H. V.; Vantzos, O.; Department of Mathematics; College of Sciences
The paper is devoted to the study of the backward behavior of solutions of the initial boundary value problem for the chevron pattern equations under homogeneous Dirichlet's boundary conditions. We prove that, as t -> infinity , the asymptotic behavior of solutions of the considered problem is completely determined by the dynamics of a finite set of functionals. Furthermore, we provide numerical evidence for the blow-up of certain solutions of the backward problem in finite time in 1D.
DEHP impairs the oxidative stress response and disrupts trace element and mineral metabolism within the mitochondria of detoxification organs
(Sage, 2025) Aydemir, Duygu; Ulusu, Nuriye Nuray; Karabulut, Gozde; Barlas, Nurhayat; KUTTAM (Koç University Research Center for Translational Medicine); KUISCID (Koç University İşbank Center for Infectious Diseases); School of Medicine; Research Center; SCHOOL OF MEDICINE
Di(2-ethylhexyl) phthalate (DEHP), a widely utilized plasticizer in various consumer products, is classified as an endocrine disruptor and has been implicated in numerous adverse health effects, including oxidative stress, inflammation, and metabolic disturbances. Despite the growing body of literature addressing the systemic effects of DEHP, the specific influence of DEHP-induced oxidative stress on mitochondrial function within detoxification organs, particularly the liver and kidneys, remains largely unexplored. This study evaluated the effects of DEHP exposure (0, 100, 200, and 400 mg/kg/day) on mitochondrial oxidative stress, trace elements, and mineral metabolism associated with signaling pathways in the liver and kidneys of rats. Altered mitochondrial oxidative stress status was indicated by impaired glucose 6-phosphate dehydrogenase (G6PD), 6-phosphoglucerate dehydrogenase (6-PGD), glutathione reductase (GR), glutathione s-transferase (GST), and glutathione peroxidase (GPx) activities, along with significant disruptions in essential minerals and trace elements, including Na, Mg, Cu, Zn, and Fe. Key oxidative stress signaling pathways, such as NF-kappa B, Akt, STAT3, and CREB, glucose, and tissue homeostasis, displayed dose-dependent responses to DEHP, indicating complex regulatory mechanisms. This study represents the first comprehensive investigation into DEHP-induced mitochondrial dysfunction, highlighting its effects on oxidative stress metabolism, trace element homeostasis, and cellular signaling pathways in detoxification organs. These findings provide novel insights into the mitochondrial mechanisms underlying DEHP toxicity and underscores the need for further research into the implications of plasticizer exposure on human health.