Recep Tayyip Erdoğan Üniversitesi Kurumsal Akademik Arşivi
DSpace@RTEÜ, Recep Tayyip Erdoğan Üniversitesi tarafından doğrudan ve dolaylı olarak yayınlanan; kitap, makale, tez, bildiri, rapor, araştırma verisi gibi tüm akademik kaynakları uluslararası standartlarda dijital ortamda depolar, Üniversitenin akademik performansını izlemeye aracılık eder, kaynakları uzun süreli saklar ve yayınların etkisini artırmak için telif haklarına uygun olarak Açık Erişime sunar.
Güncel Gönderiler
Spin–orbit coupling driven electronic phase transition and multifunctional response in lead-free K₂WCl₆ double perovskite for spintronic and energy applications
(Nature Research, 2026) Abdelgaber, M.; Elkenany, Elkenany Brens; Bouferrache, K.; Ghebouli, M.A.; Fatmi, M.; Yaylacı, Murat; Abdelghany, A.M.
A comprehensive first-principles study reveals a spin–orbit coupling (SOC)-driven electronic phase transition in the lead-free double perovskite K₂WCl₆. The material exhibits a robust non-relativistic half-metallic ferromagnetic state. The inclusion of SOC strongly reconstructs the electronic states near the Fermi level: GGA + U+SOC predicts a magnetic-semiconducting state with a global band gap of approximately 1.572 eV, whereas TB-mBJ + SOC yields a metallic state. This method-dependent relativistic response reflects a close competition among exchange splitting, on-site electronic correlation, and SOC in the W-5d manifold. This transition arises from strong relativistic effects associated with W 5d orbitals, enabling tunable electronic behavior relevant for spintronic applications. In addition to its electronic versatility, K₂WCl₆ demonstrates excellent mechanical and dynamical stability. The compound also exhibits significant spin-dependent optical and thermoelectric responses, including high ultraviolet absorption, spin-dependent dielectric behavior, and notable spin-resolved Seebeck coefficients. The estimated thermoelectric figure of merit increases with temperature and can be substantially enhanced through chemical-potential optimization, although the reported values remain dependent on the constant-relaxation-time and Slack-model approximations. These combined features highlight K₂WCl₆ as a promising multifunctional material for spin-dependent thermoelectric, spintronic, and optoelectronic applications, while experimental validation and more advanced many-body and scattering calculations remain necessary.
SML-IS: a multi-scale annotation approach to improve instance segmentation accuracy
(Nature Research, 2026) Koşar, Adem; Korkmaz, Onur Erdem; Turay, Tolga; Ergün, Ebru; Öztireli, Cengiz
Instance segmentation requires precisely outlining object boundaries in images using polygonal masks. Conventional single-scale annotations often fail to represent multi-scale appearance variations, which limits segmentation accuracy and reduces the semantic richness available to learning algorithms. We introduce Small–Medium–Large Instance Segmentation (SML-IS) labelling, a multi-scale polygon annotation strategy that provides three different annotation scales for each instance within the same image. Instead of assigning a single mask, SML-IS replicates each image and applies small, medium, and large masks for every instance, thereby tripling the number of segmentation masks while keeping the original imagery unchanged. Unlike data-augmentation methods that modify raw images, SML-IS enriches only the supervision, improving label quality and scale diversity without altering the dataset size. On a custom dataset, SML-IS consistently improves mean Average Precision (mAP) by approximately 5–6% across representative models such as Mask R-CNN and YOLOv7-seg, regardless of architectural paradigm. For domain-specific verification, the proposed method was further applied to the Kvasir-SEG colorectal polyp segmentation dataset, where SML-IS demonstrated 7% mAP gain, confirming its robustness and effectiveness in medical imaging applications. Although validated in the medical domain, the method remains broadly applicable to other visual domains such as agriculture, autonomous driving, and industrial inspection, where precise boundary delineation and high-quality annotations are essential but large-scale data collection is limited.
Do environmental taxes improve environmental sustainability beyond net-zero emissions? Evidence from ecological footprint subcomponents in the EU
(Springer Nature, 2026) Recepoğlu, Mürşit; Cay Cakir, Sümeyra; Cakir, Mehmet Ali; Artan, Seyfettin; Hayaloğlu, Pınar; Keşap, Doğan
Environmental degradation has manifested in various forms, including air and water pollution. Therefore, the impacts of environmental policies should be evaluated across all dimensions of environmental degradation. The European Union has targeted to stop CO2 emissions by 2050. Accordingly, the literature has predominantly focused on the relationship between environmental taxation and CO₂ emissions. Even if the net-zero emissions target is achieved, this does not necessarily ensure the elimination of overall environmental degradation. This study investigates the impact of environmental taxation on environmental degradation in the European Union over the period 1995–2021 using the Driscoll-Kraay (1998) estimator. The study focuses on the impact of environmental tax on ecological footprint and its subcomponents. The findings show that the ecological footprint and its subcomponents, except for built-up land and forest product footprints, can be mitigated by current environmental tax policies. However, in order to achieve net-zero environmental degradation, the European Union must reduce pressures arising from built-up land and forest product footprints. In addition to the Driscoll-Kraay (1998) estimator, the Feasible Generalized Least Squares (FGLS) estimator is employed as a robustness check, and the results remain broadly consistent across both methods. Moreover, Dumitrescu and Hurlin (2012) causality test states that strong and bidirectional causal relationships between environmental tax and ecological footprint components. This overall result confirms the existence of a green dividend within the double dividend hypothesis. It is suggested that renewable energy plants should be constructed in areas where built-up land and forest products footprint are not affected. For example, floating solar panels do not use land and also protect water bodies from evaporation.
Spatial and vertical distribution of microplastics in Arctic waters around Svalbard
(Academic Press, 2026) Öztürk, Rafet Çağrı; Terzi, Yahya; Eryaşar, Ahmet Raif; İşseven, Nisan; Gündoğdu, Sedat; Gedik, Kenan
Microplastic (MP) pollution in the aquatic environment is increasing, even in remote locations. Despite their remoteness, Arctic marine ecosystems are increasingly recognized as sinks and redistribution zones for microplastics. This study investigated the occurrence of MPs in surface and subsurface waters around the Svalbard archipelago. MP concentrations ranged from approximately 0.03 to 1.34 MP m−3 in horizontal tows and from 0.02 to 2.2 MP m−3 in vertical tows, with significantly higher mean concentrations in vertical samples (0.64 ± 0.08 MP m−3) than in horizontal samples (0.27 ± 0.04 MP m−3). A total of 17 polymer types were identified. Polyethylene terephthalate dominated both sampling modes, accounting for 68.6% of particles in horizontal tows and 64.2% in vertical tows, followed by polyethylene, polypropylene, polyamide. Polymer diversity was significantly higher in vertical samples than in horizontal ones, with Shannon index values of 0.65 ± 0.09 and 0.33 ± 0.07, respectively, although overall multivariate polymer composition did not differ significantly between sampling strategies. Vertical samples also exhibited broader heterogeneity, including increased representation of PAN, HIPS/ABS-type polymers, and rubber-derived particles at some stations. Fibers were the dominant particle shape in both sampling modes, representing 87.59% of particles in horizontal tows and 79.2% in vertical tows, while fragments, films, and beads were proportionally more frequent in vertical samples. Color composition was similarly broader in vertical tows, although black, green, and blue particles dominated both datasets. Particle size ranged from 220 to 4824 μm in horizontal samples and from 128 to 4888 μm in vertical samples, with no significant difference between sampling modes. Concentrations did not differ significantly among fjord, shelf, and offshore stations, or between stations close to and distant from settlements, once corrected for multiple testing. These results show widespread MP occurrence around Svalbard and indicate that surface-only sampling may underestimate particle abundance and compositional heterogeneity in the upper water column. Long-term monitoring that includes water-column sampling is therefore needed to improve assessments of MP transport, retention, and ecological exposure in polar marine systems. For management, these findings argue for depth-resolved sampling to be built into harmonized pan-Arctic monitoring frameworks, and for local measures, in particular improved wastewater treatment at Svalbard settlements and more strict control of fishing- and shipping-related plastic losses, to complement international action on long-range plastic transport.
Tea waste-derived wood vinegar as a bio-based acaricide: Toxicity, repellency and control of Polyphagotarsonemus latus (banks) on bean plants
(Elsevier, 2026) Akyazi, Rana; Soysal, Mete; Bayramoğlu, Zeynep; Soylu, Soner; Oğuz, Merve; Türkmen, Musa
Polyphagotarsonemus latus (Banks) (Acari: Tarsonemidae) is a major pest of numerous crops worldwide. Tea wood vinegar, derived from pyrolysed tea residues, is a sustainable pest management option. This study evaluated the ovicidal, adulticidal, and repellent activities of tea wood vinegar against P. latus under laboratory conditions and assessed its effect on mite populations on infested bean plants. Its chemical composition was analysed using GC-MS, and major volatile and phenolic compounds were identified. Ten vinegar concentrations (1%-20% v/v) were tested. Bioassays were conducted using a leaf-disc method with distilled water and calcium polysulphide as controls. Potted plant assays were also conducted to evaluate population suppression under controlled conditions. Egg mortality reached up to 94.95%, although higher concentrations caused phytotoxic effects. At non-phytotoxic concentrations (5-7.5%) in leaf discs, ovicidal activity remained high (49.5-69.7%), while calcium polysulphide showed low efficacy (3.95% mortality). Adult mortality reached 88-97% at 2.5-5% after 24 h, and repellency ranged from 96 to 100% at 5-7.5% after 96 h. LC50 values were 5.20% for eggs and 1.51% for adults, indicating effective control at non-phytotoxic levels. In potted plants, concentrations of 1-2.5% effectively reduced mite populations below the economic threshold without visible phytotoxicity, whereas higher concentrations resulted in complete suppression but caused leaf injury. Overall, tea wood vinegar showed measurable acaricidal, ovicidal, and repellent activity against P. latus under controlled conditions, with effects dependent on concentration.
