Munzur ÜniversitesiMunzur ÜniversitesiAçık Erişim Arşivi · RDL Open

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  • MakaleAçık Erişim2026Scopus SJRQ1
    A Metric-Driven Evaluation Framework for Remaining Useful Life Prognosis with Quantified Uncertainty

    Vashishtha, Govind; Chauhan, Sumika; Ertarğın, Merve

    This paper introduces a novel metric-driven evaluation framework for Remaining Useful Life (RUL) prognosis in rotating machinery, featuring robust uncertainty quantification. Accurate RUL prediction is vital for optimizing maintenance and preventing failures, but existing methods often struggle with complex nonlinear degradation or lack reliable uncertainty estimates. Our proposed framework integrates a probabilistic Deep State Space Model (DSSM) with a variational inference approach to model complex, non-linear degradation trends and inherent aleatoric uncertainty. A key innovation is the use of the Slime Mold Algorithm (SMA) for efficient hyperparameter optimization, ensuring maximum accuracy. Furthermore, an online adaptation mechanism, governed by a heuristic reinforcement learning agent, allows the model to continuously update its knowledge and adapt to concept drift in real-time. Experimental validation on the IMS bearing dataset demonstrates superior RUL prediction accuracy, evidenced by the lowest Root Mean Square Error (RMSE) of 8.1829 cycles, and a PICP of 0.59416. This dual capability makes the framework highly suitable for real-world predictive maintenance, enhancing safety and reliability.

    • SDG 9 · Sanayi, Yenilikçilik ve Altyapı
    ScopusPubMedİncele
  • MakaleAçık Erişim2026Scopus SJRQ2
    Design of Fe–35Ni/PCL nanocomposites with coupled magnetic and shape memory properties

    Kök, Mediha; Çirak, Z Deniz; Aydin, Handan; Coşkun, Meltem

    In this study, poly(ϵ-caprolactone) (PCL)-based nanocomposite films reinforced with a Fe–35%Ni alloy, which possesses a low coefficient of thermal expansion and distinct magnetic properties, were produced. The composites were prepared using the solvent casting method, with the Fe–Ni alloy incorporated into the PCL matrix at different weight ratios (10%–50%). The structural, morphological, thermal, and magnetic properties of the resulting nanocomposites were comprehensively investigated using FTIR (Fourier transform infrared spectroscopy), XRD (X-ray diffraction), SEM (scanning electron microscopy/energy dispersive x-ray spectroscopy), differential scanning calorimetry, TGA (Thermogravimetric analysis) ve (vibrating sample Magnetometry). FTIR results indicated that the Fe–Ni addition does not form chemical bonds with the PCL matrix and that the composite structure is formed through physical interactions. XRD analyses confirmed that the semi-crystalline structure of PCL is preserved and that the Fe–Ni alloy exhibits a face-centered cubic (FCC) crystal structure. SEM images revealed that while a homogeneous distribution is achieved at low doping levels, partial agglomeration occurs at high levels. Thermal analyses showed that Fe–Ni particles increase the degree of crystallization through a nucleation effect and provide a significant increase in melting temperature and crystallinity values, particularly in the 10%–40% range. TGA results revealed that the thermal stability of the composites increased and their decomposition behavior became multi-stage. Magnetic measurements showed that the saturation magnetization increased significantly with increasing Fe–Ni content, and the composites acquired ferromagnetic character. Furthermore, it was determined that the developed composites exhibit distinct shape memory behavior and can return to their original form upon thermal stimulation. The findings indicate that Fe–35%Ni-doped PCL nanocomposites are a promising candidate for multifunctional applications due to their enhanced thermal, magnetic, and smart material properties.

    ScopusWeb of Scienceİncele
  • MakaleAçık Erişim2026Scopus SJRQ1
    Evaluation and Classification of Emergency and Disaster Assembly Areas with ORESTE-Sort

    Ozdemir, Umit; Mete, Suleyman; Gul, Muhammet

    Emergency and Disaster Assembly Areas (EDAA) are designated safe zones where basic needs can be met until temporary shelters are established following natural or man-made disasters like floods, fires, earthquakes, explosions, or chemical incidents. Promptly relocating disaster victims to these areas is crucial for minimizing loss of life and facilitating effective search and rescue operations by maintaining an uninterrupted flow of information. To prepare for disasters like earthquakes, which cause significant material and emotional damage to large populations, sustainable disaster management must be ensured to evaluate site suitability, correct deficiencies, and avoid inappropriate locations. This study will examine the evaluation criteria for EDAAs established by the Tunceli Provincial Disaster and Emergency Management Authority (AFAD) in terms of area, structure, security, and accessibility, taking into account the region’s specific characteristics. Based on a literature review, eleven criteria have been proposed and ranked using the Besson mean ranking method. Areas have been classified into four categories (e.g., adequate, not suitable) using the optimistic, pessimistic, and comprise approaches of the Assignment Rule Driven by Attitudes (ARDA) and the ORESTE-Sort method. The examination of 19 EDAA provides two perspectives: an optimistic view that recommends classifying eleven areas as first class and using all areas as they are, and a pessimistic view that calls for urgent improvements in three areas and states that one area (EDAA 1) is deemed unsuitable due to its assignment to class (Formula presented.). It is also advised that the second area should not be used, despite being rated as class (Formula presented.), due to its proximity to the river and its slope characteristics. The study also performs a sensitivity analysis of the method and provides recommendations for future research.

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  • MakaleAçık Erişim2026Scopus SJRQ1
    A smartphone-based vibration dataset for induction motor fault diagnosis under different speed and load conditions

    Ertarğın, Merve; Orhan, Ahmet; Yıldırım, Özal; Chauhan, Sumika; Vashishtha, Govind

    Induction motors are foundational components across industrial applications, valued for their inherent robustness, operational simplicity, and cost-efficiency. Maintaining their reliable function is paramount for a wide range of mechanical and electrical systems. However, they are prone to various mechanical and electrical faults, such as bearing defects, rotor issues, and voltage imbalances, which can significantly impair their performance and reliability. This study presents a novel vibration dataset for induction motor fault diagnosis, uniquely acquired using a smartphone-based inertial sensor rather than conventional industrial accelerometers. Vibration signals were recorded along three orthogonal axes (gx, gy, gz), alongside gravity-compensated acceleration components (guserx, gusery, guserz), enabling detailed analysis of both raw and gravity-free vibration characteristics. Data were collected under diverse conditions, including healthy operation and several fault types, across varying rotational speeds and load states. The dataset features long-duration vibration recordings sampled at 100 Hz, suitable for both time-domain analysis and window-based feature extraction. Its inclusion of multiple operating speeds and load conditions is ideal for studying the impact of operational variability on fault signatures. By leveraging low-cost and readily accessible smartphone sensors, this dataset supports practical and accessible vibration data acquisition for supporting the development, benchmarking, and validation of data-driven fault diagnosis methods. This resource is expected to significantly advance research in condition monitoring of induction motor, particularly for machine learning and signal processing applications using vibration data.

    • SDG 9 · Sanayi, Yenilikçilik ve Altyapı
    Scopusİncele
  • MakaleAçık Erişim2026Scopus SJRQ1
    The mediating role of problem solving in the relationship between emotional intelligence and mental well-being

    Erdoğan, Ramazan; Özcan, Büşra; Kızar, Oktay; Kızılkoca, Mustafa; Çalışır, İrem Kaptangil; Bozkurt, Eyüp; Uğurlu, Fatih Mehmet; Tan, Suriye; Koçal, Meryem

    Background: This study aims to examine the relationship between emotional intelligence and mental well-being among university students and to reveal the mediating role of problem-solving skills in this relationship. Methods: Of these students, 707 participated, and the Emotional Intelligence Trait Scale, the Warwick-Edinburgh Psychological Well-being Scale, and the Problem-Solving Inventory were used as data collection tools. The SPSS software was used for data analysis. Results: Emotional intelligence appears to have a significant effect on mental well-being, and emotional intelligence directly significantly predicts problem-solving skills, but mental well-being does not have a significant effect on problem-solving skills. Emotional intelligence appears to have a direct effect on problem-solving, and mental well-being mediates this effect. The explanatory power of the model is moderate in terms of the role of emotional intelligence in predicting mental well-being and more limited in terms of its role in predicting problem-solving skills. Conclusion: In conclusion, emotional intelligence strengthens individuals’ mental well-being and directly positively impacts their problem-solving skills. However, mental well-being does not play a mediating role in the problem-solving process. This suggests that the direct effect of emotional intelligence is primary in improving problem-solving skills, and mental well-being does not serve as a decisive mediating factor in this process. Therefore, interventions aimed at strengthening emotional intelligence can be effective both in enhancing individuals’ mental well-being and in directly supporting problem-solving skills.

    • SDG 3 · Sağlık ve Kaliteli Yaşam
    ScopusWeb of SciencePubMedİncele
  • MakaleAçık Erişim2026Scopus SJRQ1
    Deep learning-based detection of bowel sound events in continuous recordings

    Çelik, Yusuf

    Accurate identification of bowel sound events is essential for the long-term and non-invasive monitoring of gastrointestinal activity. In this study, we present a band-aware multi-band deep learning approach that explicitly accounts for the distinct acoustic characteristics of bowel sounds across different frequency ranges by jointly analyzing low- and high-frequency components. The proposed method operates on time–frequency representations extracted from continuous recordings to produce frame-level bowel sound probabilities, which are subsequently integrated into recording-level decisions through a unified decision-making strategy. Despite the pronounced class imbalance in the dataset, the proposed system achieved accuracy levels exceeding 98% at the frame level and 99% at the recording level, yielding stable and consistent outcomes through probability aggregation and temporal smoothing steps. These results indicate that the proposed approach provides a reliable and well-structured framework for bowel sound event detection and establishes a solid methodological basis for the analysis of long-duration recordings.

    • SDG 3 · Sağlık ve Kaliteli Yaşam
    AtıfScopus2WoS2OpenAlex2
    ScopusWeb of SciencePubMedİncele
  • MakaleAçık Erişim2026Scopus SJRQ1
    Comparative effects of La2O3 and Sm2O3 on structural and radiation shielding properties of WO3 enriched borate glassy-ceramics

    Taşgın, Yahya; Yılmaz, Demet; Kanca, M. Sait; Yayla, Nihal; Kök, Mediha; Güler, Ömer

    This research comprehensively investigates the impact of incorporating rare earth oxides ‑samarium oxide (Sm2O3) and lanthanum oxide (La2O3)- into a borate glassy-ceramic system enriched with tungsten oxide (WO3), with a focus on both structural characteristics and radiation shielding performance. SEM-EDS, elemental mapping, and XRD analyses conducted on the synthesized glassy-ceramic samples revealed that the incorporated rare earth oxides, Sm2O3 and La2O3, were uniformly distributed throughout the glassy-ceramic matrix. The results also confirmed that the glassy-ceramic retained its inherently amorphous structure. Moreover, the nominal doping levels of the rare earth elements were found to be in agreement with both the qualitative and quantitative results obtained from EDS measurements. Also, the gamma ray shielding parameters of synthesized glassy-ceramic samples were measured in absorption geometry with Am-241, Ba-133 and Ra-226 radioactive sources. The neutron shielding parameters were theoretically calculated. The 241Am-Be fast neutron source was used to measure the equivalent dose of neutron absorption. At an incident photon energy of 74.8 keV, the mass attenuation coefficient of the tungsten oxide–enriched borate glassy-ceramic exhibited a remarkable improvement—rising by 17.98 % with the addition of 3 wt% Sm2O3 and by 11.58 % with the addition of 3 wt% La2O3. Notably, the N4 sample demonstrated a significant reduction in neutron-equivalent dose rate, reaching 19.80 % (μSv/h). The lead equivalent thicknesses (Pbeq) calculated at 356 keV were 0.02397 cmPb for N0, 0.0391 cmPb for N1, 0.0403 cmPb for N4, and 0.0389 cmPb for N7. When benchmarked against the undoped N0 sample, the N4 and N7 compositions exhibited reductions in Pbeq values by approximately 68 % and 62 %, respectively, indicating a marked improvement in gamma shielding efficiency. Among all tested formulations, the Sm2O3-doped variant demonstrated superior gamma-ray attenuation capability relative to the La2O3-doped glassy-ceramic. Furthermore, the N4 sample achieved an impressive thermal neutron attenuation rate of 96.46 %, underscoring its strong potential as an effective dual-purpose shielding material against both thermal neutrons and ionizing gamma radiation.

    AtıfScopus1
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  • MakaleAçık Erişim2026Scopus SJRQ1
    Effect of Y2O3 rare earth oxide on the microstructure and growth kinetics of TiO2-based ceramic coatings fabricated by micro arc oxidation

    Ayday, Aysun; Duru, Erhan; Kırsever, Derya; Doğan, Fatih

    This study investigates the influence of Y2O3 addition on the microstructure, growth kinetics, and mechanical properties of TiO2-based ceramic coatings formed on Ti–6Al–4V alloy through the Micro Arc Oxidation (MAO) process. The experiments were carried out using Ti–6Al–4V plates coated in silicate-based electrolytes, with and without 1 g/L Y2O3, under a constant current density of 5 A/dm2 and a voltage of 360 ± 20 V for different treatment times (1, 3, 7, and 10 min). The coatings were evaluated by weight gain measurements, SEM/EDS analyses, X-ray diffraction (XRD), and constant load scratch testing supported by profilometry. Results revealed that Y2O3 significantly accelerated coating growth during the initial stages, leading to higher weight gains and denser, less porous morphologies compared to Y2O3-free coatings. XRD analysis indicated amorphous TiO2 and anatase phases at short durations, while rutile formation became dominant with longer treatments. Kinetic modeling demonstrated that both coatings initially followed a linear reaction-controlled mechanism (n ≈ 1), with calculated growth constants of 3.44 × 10⁻4 mg/mm2·s for Ti-MAO and 7.45 × 10⁻4 mg/mm2 s for Ti–Y2O3–MAO. However, after approximately 420 s, the Y2O3 coatings exhibited a marked reduction in growth rate due to electrical insulation effects of the thickened ceramic layer, resulting in multi-stage kinetics. Constant load scratch testing showed that Y2O3 incorporation reduced groove depth and width by nearly 45%, improving adhesion strength and mechanical durability. These findings confirm that rare-earth oxide addition is an effective strategy for enhancing the performance of MAO coatings on titanium alloys.

    AtıfScopus2WoS1OpenAlex2
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  • MakaleAçık Erişim2026Scopus SJRQ3
    Changes in common carp (Cyprinus carpio) sperm quality and membrane lipid composition related to cryopreservation by Tribulus terrestris; [Alterações na qualidade do esperma e na composição lipídica da membrana da carpa comum (Cyprinus carpio) relacionadas à criopreservação por Tribulus terrestris]

    Ölçülü, Abdullatif; Özçiçek, Esin; Kocabaş, Filiz Kutluyer; Kocabaş, Mehmet; Kızak, Volkan; Yilmaz, Ökkeş

    Docosahexaenoic acid (DHA) was the major polyunsaturated fatty acid (PUFA) in the sperm plasma membrane, and the levels of PUFAs decreased in treated groups during the cryopreservation process. The supplementation of TT (Tribulus terrestris) to Cyprinus carpio sperm at 200 µg∙L-1 positively affected the maintenance of motility parameters and FAs levels after the freeze-thaw cycle, and TT can be used as an herbal medicine instead of synthetic pharmaceuticals to improve the productive performance in aquaculture.

    • SDG 2 · Açlığa Son
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  • MakaleAçık Erişim2026Scopus SJRQ1
    The effectiveness of AgNPs synthesized using Aspergillus floccosus for controlling Phoma herbarum and Aphis Pomi de Geer

    Aker, Onur; Bektaş, İdris; Yazdıç, Ferit Can

    This study was conducted to synthesise silver nanoparticles (AgNPs) using Aspergillus floccosus fungal extract and to evaluate the pesticidal efficacy of the resulting nanopesticide product against two harmful organisms (pathogenic fungus and pest) affecting apples. The synthesised AgNPs were subjected to a series of characterisation tests (UV-Vis, FTIR, XRD, SEM, TEM, EDX, Zeta Potential) and, based on the results obtained, the AgNPs synthesis was successfully completed. Within the scope of this study, the first registration process has been carried out for the fungal pathogen (Phoma herbarum) that causes rot disease in apple fruits. The fungicidal efficacy of five concentrations of AgNPs (10, 25, 50, 100, and 200 mg L⁻¹) was evaluated against this pathogen under both in vitro and in vivo conditions. The results showed that AgNPs exhibited a significant inhibition on the mycelial growth of Phoma herbarum in vitro. The 200 mg L⁻¹ concentration showed the highest inhibition percentage (81.5%). Concerning in vivo test, the effect of AgNPs on disease severity index of Phoma herbarum in apple fruits was evaluated. The result of this part showed that the concentration 200 mg L⁻¹ of AgNPs exhibits highest fungicidal efficacy disease reduction rates (100%), Following by 67% for AgNPs 100 mg L⁻¹. The insecticidal effects of AgNPs on fourth-stage nymphs and adults of the pest (Aphis pomi) were evaluated in laboratory and field applications. For this purpose, AgNPs prepared at five different concentrations (30, 60, 90, 120, and 150 mg L⁻¹) were sprayed on the pests. The results showed that the insecticidal efficacy of AgNPs against Aphis pomi was directly related to both the dose and the exposure time. Specifically, the lethal concentration required to kill adults (LC50: 48.9 mg L⁻¹ for laboratory application and 68.4 mg L⁻¹ for orchard application) was higher than the dose required for nymphs (LC50: 32.3 mg L⁻¹ for laboratory and 52.1 mg L⁻¹ for orchard application). A similar trend was observed for lethal time, with adults exhibiting longer required exposure times (LT50: 51.2 h in the lab and 58.4 h in the orchard) compared to nymphs (LT50: 42.0 h in the lab and 45.1 h in the orchard). According to the results obtained, AgNPs synthesised using Aspergillus floccosus fungus have been proven to be highly effective at low doses against two major harmful organisms that cause qualitative and quantitative losses in apples. In conclusion, it has been proven that this silver-based nano pesticide product can be used as an alternative and innovative product in combating factors that cause agricultural damage to protect apple health.

    • SDG 2 · Açlığa Son
    • SDG 3 · Sağlık ve Kaliteli Yaşam
    AtıfScopus1WoS1
    ScopusWeb of SciencePubMedİncele
  • MakaleAçık Erişim2026Scopus SJRQ2
    Effects of Magnetic Abrasive Finishing Process Parameters on the Inner Surface Machining of AISI 304 Austenitic Stainless Steel Pipes

    Sarıçiçek, İzel; Çaydaş, Alparslan Ulaş; Cihangir, Salih; Say, Yakup

    In this study, the effects of SiC abrasive ratio, size of magnetic Fe particles and the machining time parameters on the surface roughness, material removal rate, roundness of the holes and corrosion resistance in magnetic abrasive inner surface finishing (MAF) of the AISI 304 austenitic stainless steel pipes were experimentally investigated. A Taguchi L9 orthogonal array was used for the experiments. The surface roughness and the characteristics of the machined surfaces were examined by using the3D surface topography method. The characteristics of the abrasive and magnetic powders before and after machining operations were investigated under scanning electron microscope (SEM) and x-ray diffraction analysis (XRD) techniques. The electrochemical corrosion measurements were performed in 3.5 wt.% NaCl solutions in a typical three-electrode electrochemical cell. An analysis of variance (ANOVA) method was also applied to the study in order to determine the statistical effects of each factor on the measured responses. Consequently, AISI 304 samples machined with MAF technique revealed better results for corrosion performance, surface quality, material removal rate and the hole dimensional tolerances.

    AtıfScopus1WoS1OpenAlex1
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  • MakaleAçık Erişim2026Scopus SJRQ2
    Single-Ended Fault Detection and Fault Location in Transmission Lines Using Approximate Derivative

    Akdağ, Mustafa; Mamiş, Mehmet Salih; Akmaz, Düzgün

    Fault location in power transmission lines (PTLs) relies on impedance or traveling wave (TW) principles. TW approaches offer superior accuracy and high robustness against fault resistance. While multi-ended methods require precise terminal synchronization, single-ended TW (SETW) methods utilize measurements from one terminal, requiring accurate distinction of reflected waves. This study employs the computationally efficient approximate derivative (AD)—the difference between consecutive samples—for SETW fault detection and location. Normally near zero, the AD of modal signals produces sharp transitions during faults. Comparing AD output to a threshold achieves fault detection. The AD then identifies arrival times of the incident and reflected TWs. When using TW theory to distinguish reflections from the fault point and remote end, the fault distance is calculated from their arrival time difference. Validated through 293 diverse ATP simulated fault scenarios, the approach delivered highly accurate results despite using a lower sampling rate than established methods, utilizing an exceptionally short data window—only 2.03 ms for a 300 km line. Finally, operational boundaries for the signal-to-noise ratio (SNR) in noisy conditions are established.

    • SDG 9 · Sanayi, Yenilikçilik ve Altyapı
    ScopusWeb of Scienceİncele
  • MakaleAçık Erişim2026Scopus SJRQ1
    The effect of hydrostatic water level on the local scour downstream of plunging aerated jets

    Tunc, Mustafa; Aytac, Ayca; Tuna, M. Cihat; Acar, Ramazan

    This paper reports an experimental study on the effect of hydrostatic water level on local scour downstream of plunge aerated jets. To examine the shape of the scour for non-cohesive bed material, different flow and air rates, and different aeration capabilities, hydrostatic water level circumstances were tested. The water jets were aerated using conduit systems with varying cover opening ratios. Measurements were made to determine the length of the scour hole, the value of the maximum scour depth, the location of the maximum scour depth, and the scour hole profile in equilibrium. The current findings show that downstream hydrostatic water levels have a significant impact on the maximum depth and area of scour. Additionally, it was discovered that the conduit gate opening ratio and aeration performance (Qa/Qw) are crucial factors that affect the geometry and diameters of scour holes. The properties of scour caused by various hydrostatic levels were systematically compared to develop empirical correlations for predicting the maximum scour depth. Consequently, predictive emprical formulas incorporating these hydrostatic variations and aeration parameters are presented to improve engineering design accuracy.

    • SDG 6 · Temiz Su ve Sanitasyon
    ScopusWeb of SciencePubMedİncele
  • MakaleAçık Erişim2026Scopus SJRQ2
    The Relationship Between Agricultural Carbon Dioxide Emission and Agriculture Subsectors Production: Static Panel Data Approach

    Peker, Ayşe Esra; Akdağ, Nuran; Veysikarani, Dilek; Kaya, Mustafa Göktuğ; Kaya, Perihan Hazel

    Human activities contribute to carbon dioxide (CO₂) emissions, which have serious environmental, economic, and social effects of climate change. This has sparked efforts to find large-scale solutions to eliminate the causes of climate change. While these solutions mainly involve reducing carbon emissions through global agreements, individual nations have also taken steps to cut emissions by changing production methods, such as irrigation and fertilisation, to ensure the efficient and effective use of resources and the proper storage and transportation of food. As a result, the agricultural sector is both a source and a victim of this process. The sector’s environmental impact varies due to differing production techniques and energy needs across various sub-sectors like vegetable, grain, and fruit production. Increases in carbon dioxide emissions in this sector are connected not only to production activities but also to demographic and social factors, such as the rural population proportion. This study aims to explore the effect of vegetable, grain, and fruit production, as well as the rural population ratio, on carbon dioxide emissions. To achieve this, a static panel data analysis was conducted across 21 European countries from 1970 to 2023. According to the research findings, vegetable production increases carbon emissions from agriculture. However, it was found to have a significant, albeit borderline, impact on fruit production and to reduce carbon emissions. These results demonstrate that agriculture's contribution to carbon dioxide emissions varies by sub-sector and provide valuable information for developing sustainable agricultural policies.

    • SDG 2 · Açlığa Son
    • SDG 13 · İklim Eylemi
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  • MakaleAçık Erişim2026Scopus SJRQ3
    CFD Simulation of Aerodynamic Forces on a Simplified Heavy Vehicle Model with Steady Base Blowing

    Firat, Erhan; Seydhan, Mehmet

    A numerical investigation was conducted to examine the flow around a European tractor-trailer combination model (GETS) using a steady RANS model k-ω SST at a Reynolds number of 100000. Experimental aerodynamic force measurements were also carried out for the purpose of validating the CFD simulations. The present paper focuses on the effect of steady blowing from the thin slots positioned on the rear surface (base) of the model on the aerodynamic characteristics of the GETS. The combination of three key parameters was tested: the jet-to-freestream velocity ratio (VR), the inclination angle of the jet (θ), and the jet’s location. More than 100 CFD simulations were performed over a range of key parameters. The findings indicate that the jet direction’s inclination towards the rear surface typically leads to a modest yet favorable effect on the drag reduction. It has been demonstrated that increasing the VR to 2 has the potential to reduce aerodynamic drag by up to 50%. However, it is also demonstrated that employing VR values greater than approximately 1.25 is not viable in terms of active flow control efficiency. At θ=0°, the active control efficiency of the both-jets configuration is approximately 6 for VR=0.5 and approximately 1.6 for VR=1. The total drag coefficient on the model is reduced by 8.3% and 17.7% for the VR=0.5 and 1 cases, respectively. It has been demonstrated that the viscous components of total drag and lift are independent of jet configuration, VR, and θ. In both upper and lower jet configurations, it is possible to increase or decrease the aerodynamic lift acting on the model by changing the inclination angle.

    Scopusİncele
  • MakaleAçık Erişim2026Scopus SJRQ2
    Multi-functional GeAg- and TiO2-modified diamond-like carbon thin film device: structure, surface properties, photoresponse, photosensitivity, and biological performance

    Aslan, Naim; Şükrü Kurt, Mustafa; Mehmet Koç, Mümin; Yilmazer, Yasemin; Coskun, Burhan; Aksakal, Bünyamin

    DLC films represent a promising class of materials that can be used in various applications due to their optical, optoelectronic, tribological, and biomedical characteristics. In this work, GeAg- and TiO2-modified DLC thin films were prepared using the magnetron sputtering method under ultrahigh vacuum conditions. DLC thin film characteristics and addition of GeAg and TiO2 into the DLC structure were confirmed and subsequently assessed via scanning electron microscopy (SEM), atomic force microscopy, energy dispersive x-ray spectroscopy, x-ray photoelectron spectroscopy, and Raman spectroscopy. DLC thin film thicknesses were determined via SEM and found to be 235 nm and 380 nm for DLC/TiO2 and DLC/GeAg thin films, respectively. Contact angle and surface wettability analyses were performed for uncoated glass, GeAg- and TiO2-modified DLC thin films. The antibacterial properties of the DLC films were assessed for E. coli and S. aureus. The biocompatibility of these same films was confirmed using the L929 cell line, where no toxic effect was evidenced. To elucidate the optical characteristics of the thin films, a UV–vis spectrum was obtained, and band gap energies were proposed using these data. Photoresponse characteristics of the DLC thin films were assessed under varying illumination using current–time plots. It could be seen that DLC thin films’ responsiveness to light was dependent on illumination intensity. The results demonstrate that nanostructures are good candidates for multifunctional applications exhibiting good antibacterial and photoresponsive characteristics with outstanding biocompatibility.

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  • MakaleAçık Erişim2026Scopus SJRQ3
    Functional magnetic polymer nanocomposites: Fe2O3/Fe3O4-enhanced PCL-PVA materials

    Deniz Çirak, Zehra; Aydin, Handan; Coşkun, Meltem; Kök, Mediha

    In this study, magnetic polymer nanocomposites based on PCL/PVA PCL(Polycaprolactone)-PVA(Polyvinyl alcohol) (80/20) reinforced with Fe2O3 and Fe3O4 nanoparticles were successfully produced, and their thermal, structural, morphological, and magnetic properties were comparatively investigated. The systematic evaluation of the effects of Fe2O3 and Fe3O4 additions on the same biodegradable polymer matrix at 20% and 40% loading levels constitutes the main novelty of this study. The nanocomposites were characterized using thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM), and physical property measurement system (PPMS) analyses. The TGA results demonstrated that the decomposition onset temperature increased with the addition of nanoparticles and, particularly in the composite with 40% Fe3O4 content, the residual mass reached 15.81%, indicating a significant improvement in thermal stability. DSC analyses showed that the melting peak temperature increased at high loading levels and that Fe2O3 loading supported crystallization more than Fe3O4. FTIR and XRD results confirmed that the nanoparticles dispersed successfully in the polymer matrix without forming chemical bonds and provided strong interfacial interactions. The SEM images revealed a homogeneous distribution at low loading levels, while significant agglomeration formed at high Fe3O4 content. Magnetic measurements indicated that the pure PCL/PVA blend exhibited diamagnetic behavior, Fe2O3-containing composites displayed hard ferromagnetic behavior, and Fe3O4-containing composites exhibited soft ferromagnetic behavior. The highest saturation magnetization of 10.4 emu/g was obtained in the composite with 40% Fe3O4 content. The findings indicate that Fe2O3- and Fe3O4-doped PCL/PVA nanocomposites are functional materials with high potential for applications in sensors, actuators, magnetically controlled systems, and biomedical applications.

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  • MakaleAçık Erişim2026Scopus SJRQ1
    Preparation of Nanographene-Based Copolymer Nanocomposites: Thermal Decomposition Kinetic, Optical, and Electrical Behaviors

    Barim, Esra; Demirelli, Kadir

    The poly(4-methacryloyloxyphenyl-4'-methoxystyryl ketone-co-methyl methacrylate) [P(MPMESK0.25-co-MMA)] was synthesized using a free radical copolymerization method at 60 °C. The composition of the copolymer was estimated by 1H-NMR. The nanocomposites of P(MPMESK0.25-co-MMA)-loaded 9 and 11 wt% nanographene (NG) were produced using the ultrasonic homogenizer sonicator. The FT-IR, 1H-NMR, GPC, TGA, XRD, and SEM techniques were used to characterize the copolymer and composites. The thermal behavior of P(MPMESK0.25-co-MMA) partially heated up to 270, 310, 340, and 380 °C was investigated by FT-IR analysis. A six-membered anhydride ring in the copolymer backbone formed at 340 °C and higher temperatures. TG measurements were used to analyze the thermal decomposition processes of pure P(MPMESK0.25-co-MMA) and P(MPMESK0.25-co-MMA)/NG 11 wt% composite. Apparent activation energies for thermal decomposition of P(MPMESK0.25-co-MMA)/NG 11 wt% were determined using the Flynn–Wall–Ozawa (FWO) and Kissinger–Akahira–Sunose (KAS) methods at a temperature range of 200 and 400 °C for a weight loss of approximately 70%. The average activation energies determined from the FWO and KAS methods were 86.3 and 80.3 kJ/mol, respectively. The dielectric and electrical behaviors of the P(MPMESK0.25-co-MMA) and P(MPMESK0.25-co-MMA)/NG 11 wt% composite were investigated at room temperature. The dc activation energy for dc conductivity of nanocomposite was calculated as 1.092 eV. Optical properties such as absorption, reflectance, refractive index, absorption edge, direct band gap of the copolymer, and composites were investigated from their optical examinations in the wavelength region of 200–800 nm. It was found that the optical energy gap values had shifted to the lower energies with the doping of NG.

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  • MakaleAçık Erişim2026Scopus SJRQ1
    Modulation of SIRT1/PPARγ pathways and tight junction proteins by nicotinamide riboside under chronic variable stress

    Celik, Abdullah; Sahin, Nurhan; Orhan, Cemal; Er, Besir; Erten, Fusun; Ozmen, Busra; Tuzcu, Mehmet; Ozercan, Ibrahim Hanifi; Sahin, Kazim

    Abstract: Chronic stress disrupts homeostasis, leading to major health problems such as liver damage, intestinal barrier dysfunction, and impaired glucose metabolism. Although current treatments, including anxiolytics, sedatives, antidepressants, and beta blockers, are effective, their adverse effects emphasize the need for safer alternatives. Nicotinamide riboside (NR), a precursor of nicotinamide adenine dinucleotide (NAD+), plays a central role in energy metabolism and oxidative stress regulation; elevated NAD + levels have been associated with reduced risk of chronic diseases such as obesity and type 2 diabetes. However, the effects of NR on liver metabolism, intestinal barrier integrity, and related protein pathways remain unclear. This study investigated the effects of NR supplementation in rats exposed to chronic variable stress (CVS). Fifty-six male Sprague Dawley rats were divided into normal and CVS groups and treated in a 2 × 4 factorial design with 0, 150, 300, or 600 mg/kg NR. Under CVS conditions, serum glucose, corticosterone, ACTH, and insulin levels increased, whereas NAD+, NADPH, nicotinamide (NAM), and nicotinic acid (NA) decreased significantly (p < 0.001). NR supplementation effectively corrected these biochemical imbalances and upregulated hepatic markers, including PPARγ, SIRT1, GLUT2, IRS1, and FASN (p < 0.001). Furthermore, the increased expression of key transport proteins such as PepT1, LAT2, EAAT3, FABP2, and FATP4 contributed to maintaining intestinal barrier integrity and improving gut health. NR also promoted the recovery of tight and adherens junction proteins. Notably, high-dose NR (600 mg/kg) markedly alleviated liver fibrosis, improved glucose metabolism, and strengthened intestinal barrier function, demonstrating its therapeutic potential as an alternative strategy against stress-induced metabolic disorders. Key points: • NR mitigated chronic stress-induced liver, intestinal, and glucose dysregulation. • NR improved glycemia and NAD⁺-related biomarkers under stress. • NR reduced hepatic fibrosis markers. • NR strengthened TJ/AJ proteins, supporting intestinal barrier integrity. • Findings support NR’s therapeutic potential in stress-related metabolism.

    • SDG 3 · Sağlık ve Kaliteli Yaşam
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  • MakaleAçık Erişim2026Scopus SJRQ4
    Petrography, geochemistry and formation of the Sarıçimen (Van, eastern Türkiye) Fe-Ni-Co laterite deposit

    Çimen, Okay

    The Sarıçimen Fe-Ni laterite deposit is located in eastern Türkiye (Van province) and represents one of the important Ni and Co-enriched lateritic mineralizations formed in the ophiolitic occurences. This study aims to decipher the petrographic and geochemical signatures of the laterite horizon in order to better figure out the processes controlling Fe-Ni-Co mineralization and the genesis of the deposit. In this study, field and petrographic observations, and whole-rock geochemical data have been used to characterize the mineralogical and geochemical evolution of the lateritic horizon. Petrographic studies indicate that the protolith of the laterite zone is mostly composed of serpentinized ultramafic rocks including relics of Cr-spinel and chromite grains. This lateritic zone is characterized by hematite-and magnetite-rich zones formed above saprolitic levels that may have been derived from the weathering of ultramafic parent rocks. Whole rock geochemical analyses indicate that Fe₂O₃ and SiO₂ are the dominant oxides, and Ni concentrations vary between 0.33 and 1.01 wt.%. Also, Co values are ranging between 330 ppm and 600 ppm in the laterite samples investigated here. More importantly, correlation analyses exhibit a positive relationship between Ni and Fe₂O₃ and this may be attributed to a close association with Fe-oxide minerals during the lateritization. In contrast, a negative correlation between Ni and SiO₂ may indicate the presence of silica depletion during chemical weathering. The geochemical trends investigated here reveal that the laterite zone developed through intense lateritic weathering of ultramafic rocks, which is characterized by the removal of relatively mobile elements such as Si and Ca and the residual enrichment of Fe, Ni, and Co. The presence of Cr-spinel relics once again confirms the ultramafic origin of the parental rocks. Overall, the Sarıçimen deposit represents a Fe-Ni-Co laterite derived from nearby ultramafic sources within the ophiolitic sequence. The occurrence of Fe-Ni-Co laterite deposits at both the southwestern and northeastern segments of the Southern Neotethys Suture Zone suggests that this tectonic belt may represent a promising metallogenic area for lateritic Fe-Ni-Co mineralization in the southern Türkiye.

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