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
Investigation of the stacking sequence and cutting parameters effect on hole morphology in hybrid FML composites
(Elsevier, 2025) Doğan, Mehmet Aki; Yapıcı, Ahmet; Gemi, Lokman; Yazman, Şakir; Morkavuk, Sezer; Köklü, Uğur
Fiber metal laminates (FMLs) are widely used in a wide range of engineering applications, especially in the aerospace industry, due to their superior functional properties and low cost. In this experimental study, hybrid FML composite specimens consisting of five different Al2024/FRP/Al2024 stacked glass and carbon fiber layers were fabricated to investigate the effect of stacking sequences and cutting parameters on the drilling process. The drilling machinability properties of the specimens were investigated by considering the cutting force, torque, surface roughness and damage analyses in the hole after drilling and the results are presented comparatively. As a result of the experimental study, it was determined that the stacking sequences have a significant effect on the machinability. In terms of cutting forces, it was observed that the cutting force increased in carbon stacked areas and the cutting forces tended to decrease in glass stacks. In torque values, there is an increase in glass stacks and a decrease in carbon stacks. The highest roughness values were measured from all-glass stacked specimens. In hybrid composites, it was observed that glass stacks generally increased the surface roughness.
Cancer patients’ attachment styles in the first year after diagnosis: the impact of perceived stress and emotion regulation skills
(AVES, 2025) Bacık Yaman, Gözde; Kayıkçıoğlu, Erkan; Hocaoğlu, Çiçek
Background: This study aimed to determine the magnitude of perceived stress among cancer patients in the first year of diagnosis and to reveal the effects of stress levels and emotion regulation skills on attachment styles. Methods: This cross-sectional study involved 200 patients enrolled in a medical oncology outpatient clinic in the first year of cancer diagnosis. Attachment styles were determined using the Adult Attachment Style Scale. Stress levels and emotion regulation skills were assessed with the Perceived Stress Scale (PSS) and the Emotion Regulation Skills Questionnaire (ERSQ). The participants were questioned about their cohabitant status and caregiver preferences. Results: The analyses revealed that almost half of the participants (n = 99) had high stress levels (P = .001), and most (69%) had a secure attachment style. The results indicate that secure attachment styles had a weak negative correlation with PSS scores (r = −0.191; P = .007) and a weak positive, statistically significant correlation with ERSQ scores (r = 0.297; P < .001). The study found that perceived stress during the first year after diagnosis had a significant effect on the development of insecure attachment styles (Exp(B): 1.051; 95% confidence interval (CI), 1.009-1.095; P < .05). Emotion regulation skills affect insecure attachment styles, as indicated by the statistical analysis (Exp(B): 0.982; 95% CI, 0.965-0.999; P < .05). Conclusion: Our findings support the idea that stress levels and emotion regulation affect attachment styles. Awareness of attachment theory and the effects of different forms of insecure attachment on patients is essential to improving their ability to better understand and meet their support needs.
Strength evolution and carbonation behavior of red mud–fly ash geopolymers under varying pre-curing conditions
(Elsevier, 2025) Wu, Guowei; Bai, Jinwen; Yılmaz, Erol; Feng, Guorui; Han, Yanna; Li, Jian
Harnessing red mud (RM) and fly ash (FA) on a large scale could transform these industrial byproducts into valuable resources, driving greener, low-carbon advancements in the aluminum industry. Mastering mechanical and carbon sequestration behaviors of RM-FA based geopolymer grouting materials will provide theoretical support for achieving this goal. The carbonation characteristics, including depth, area, and CO₂ absorption rate, were evaluated for specimens with different precuring durations via phenolphthalein titration and gravimetric methods. The mechanical features of carbonation-cured materials were then tested. Through wide-ranging microstructural characterization systems (XRD, FTIR, SEM-EDS, TG-DTG, and LF NMR), evolution of phase composition, microstructure, and pore-fracture features during both carbonation and geopolymerization processes was systematically explored under varying precuring conditions. Results demonstrate that extending pre-curing duration significantly mitigates NaHCO3-induced obstruction of CO2 diffusion channels, increasing carbonation depth from 1.01 ± 0.05 mm to 5.07 ± 0.11 mm (RSD＜5.0 %). In specimens with shorter pre-curing periods, elevated free alkali content enhances CO₂ absorption to 2.29 ± 0.07 % (RSD＜5.0 %) (C1P). Notably, C14P specimens achieve maximum CO2 sequestration of 30.9 kg/ton through CaCO3 formation, benefiting from both unimpeded CO2 diffusion (absence of excessive NaHCO3 blockage) and sufficient Ca2 + availability. The 40.58 % strength deterioration in C1P specimens stems from the competition between early-stage geopolymerization and carbonation reactions. Subsequent standard curing promotes the growth of Na2CO3/CaCO2 crystals and further drives geopolymerization, thereby significantly reducing the final strength degradation rate of the specimens. Microstructural analysis confirms that carbonation-induced suppression of N(C)-A-S-H gel/ettringite formation increases total pore volume, constituting the primary reason for strength degradation. These findings systematically elucidate the interaction mechanisms between geopolymerization and carbonation reactions under varying pre-curing conditions, providing a theoretical basis for synergistically optimizing the CO₂ sequestration capacity and mechanical performance of RM-FA based geopolymer materials.
Spontaneous reverse seroconversion in resolved hepatitis B infection
(Elsevier, 2025) Özşahin, Aybegüm; İlgar, Tuba
Dear Editor;
We read with great interest the article by Çerik and Aldemir
reporting a rare case of spontaneous reactivation of resolved hepatitis B
virus (HBV) infection in the absence of immunosuppression [1]. In
accordance with their findings, we would like to share a case in which
reverse seroconversion (HBV-RS) occurred despite the absence of
ongoing immunosuppressive therapy.
Assessing microplastic contamination and health risks in infant formula: A case study from Turkey
(Elsevier, 2025) Şirin, Murat; Mutlu, Tanju; Eryaşar, Ahmet Raif; Gedik, Kenan
Microplastic (MP) contamination is an emerging concern for food safety and infant health. This study provides the first systematic assessment of MPs in infant formulas marketed in Turkey. A total of 36 samples from 12 commercial brands were analyzed using stereomicroscopy and micro-Raman spectroscopy. Analyses were performed with 532 and 785×nm lasers, 50 × magnification, 10 s exposure, a 300–3200 cm−1 spectral range, and gratings of 600/1200 l/mm. Suspected particles were compared against the ST-Japan MP library, with a ≥70 % spectral match threshold applied for polymer identification. MPs were detected in 100 % of samples (n = 36), with 97 % of particles successfully characterized. Concentrations ranged from 14 to 52 MPs/100 g (mean 31.3 MPs/100 g). Fibers were the dominant form (58 %), followed by fragments and films. Nine polymers were identified, with polyethylene (PE), polyethylene terephthalate (PET), polypropylene (PP), and polyamide (PA) most abundant. Packaging materials, manufacturing processes, and feeding equipment were identified as likely contamination sources. Estimated daily intake for infants aged 0–6 months averaged 5.64 MP/kg bw/day (∼15,400 MPs annually). This annual exposure estimate was calculated based on an assumed body weight of 7.5 kg for a 6-month–old infant and a daily formula consumption of 135 g, as recommended in previous nutritional intake assessments. To enhance toxicological relevance, mass- and surface–area–based exposures were also calculated, averaging 326.77 μg/kg bw/day and 0.009 cm2/kg bw/day, respectively. The polymeric risk index (pRi) ranged from 8.27 to 1647.65 (mean 472.12), classifying 50 % of samples as low risk, 33.3 % as high risk, and 8.3 % as very high risk. These findings confirm infant formulas as a consistent source of MP exposure and highlight the need for stricter production and packaging controls to reduce early–life risks.
