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
Design and biological evaluation of a quinoline-substituted silicon phthalocyanines for photodynamic therapy of endometrial cancer: topoisomerase IIα targeting and apoptosis induction
(Elsevier, 2026) Seyhan G.; Ali, Yasemin Altun; Barut, Elif Nur; Amin, Manar M.; Keleş, Turgut; Sari, Suat; Barut, Burak
In this study, to discover potentially selective and safe therapeutic candidates for photodynamic therapy (PDT), new quinoline-derived silicon phthalocyanine compounds (8K-C3-D-Si and 8K-C3-D-SiQ) were synthesized, characterized, and their PDT potential was evaluated. The synthesized compounds were characterized using spectroscopic methods such as FT-IR, 1H NMR, 13C NMR, MS, and UV–Vis. In photochemical measurements, the singlet oxygen production capacities and photostabilities of the compounds were investigated, and observed that 8K-C3-D-SiQ exhibited a higher effectiveness (ΦΔ = 0.088 ± 0.009 for 8K-C3-D-Si and ΦΔ = 0.345 ± 0.034 for 8K-C3-D-SiQ). The IC50 value of 8K-C3-D-SiQ in the human endometrial cancer cell line (HEC-1B) after 24 h of incubation in the presence of light was found to be 84.18 ± 14.84 nM. In cells treated with 0.1 μM 8K-C3-D-SiQ, late apoptosis was detected at 54.03 ± 3.10% and necrosis at 22.74 ± 5.98% under light exposure. At the molecular level, western blot results showed increased p53 and cytochrome c expression and suppression of topoisomerase IIα (Topo-IIα). Ab initio quantum mechanics (QM) predicted its electronic structure and molecular docking with DNA-Topo-II complex indicated that, with a unique binding, 8K-C3-D-SiQ could wrap around the DNA G-segment with two 1-methylquinolinium-8-oxypropyl substituents occupying both DNA cleavage sites. In conclusion, 8K-C3-D-SiQ may be considered a promising candidate for PDT due to its high singlet oxygen production, potent phototoxicity, topoisomerase inhibition, and apoptosis induction.
Radiological safety assessment of chestnut (Castanea sativa) from Sinop province, Türkiye: Gamma spectrometric determination of natural radionuclides and associated health risks
(Elsevier, 2026) Umar, Muttaka; Dizman, Serdar; Şahin, Tamer; Özçelik, Ali Erdem
Naturally occurring radionuclides in foodstuffs are an important pathway for internal radiation exposure in humans. This study quantifies primordial radionuclides (238U, 232Th, 40K) in chestnut (Castanea sativa) from Sinop Province, Türkiye, and evaluates the associated radiological health risks from dietary intake. Thirty composite chestnut samples were analyzed using high-purity germanium (HPGe) gamma-ray spectrometry. Mean activity concentrations were 2.19 ± 0.20 Bq kg−1 for 238U, 2.60 ± 0.30 Bq kg−1 for 232Th, and 42.6 ± 1.5 Bq kg−1 for 40K, while 137Cs was below the minimum detectable activity in all samples. Using the national per capita chestnut consumption rate (0.7 kg y−1), the average total radionuclide intake was 90.94 ± 3.01 mBq day−1. The corresponding annual effective ingestion dose ranged from 0.84 ± 0.05 μSv y−1 to 3.68 ± 0.29 μSv y−1, and the excess lifetime cancer risk ranged from 12.85 ± 0.72 × 10−7 to 54.85 ± 2.06 × 10−7. These values are well below the public dose limit of 1 mSv y−1 recommended by the International Commission on Radiological Protection and below commonly accepted radiological risk thresholds. The absence of detectable 137Cs and the relatively low 238U, 232Th, and 40K levels indicate that chestnut consumption from Sinop does not pose an appreciable radiological health risk. The data also provides a food-based radiological baseline prior to operation of the planned nuclear power plant in the region. This baseline is relevant for future environmental radioactivity monitoring, food safety and regulatory control, and sustainable agricultural management in areas affected by current or prospective nuclear facilities.
Crystal-length optimization in 681-nm pumped Tm:YAG and Tm:LuAG lasers: from low threshold to SESAM Q-switching
(Elsevier, 2026) Kaya, Fatma; Bilici, Hatice; Sumpf, Bernd; Demirbaş, Ümit; Beyatliı Ersen
We systematically quantify how crystal length governs efficiency, tuning bandwidth, and passive Q-switching in 681 nm tapered-diode-laser (TDL) pumped Tm:YAG (1.5 at.%) and Tm:LuAG (2 at.%) oscillators. By scanning four lengths (3, 5, 7, and 9 mm), we identify a three-way trade-off among pump absorption, quasi-three-level reabsorption, and length-dependent passive loss. In continuous-wave (CW) operation, maximum extraction occurs at 7 mm in both hosts, while the minimum absorbed lasing thresholds are obtained with the 3 mm crystals (35–45 mW). In the experiments, instantaneous slope efficiencies reach 60% (Tm:YAG) and 52% (Tm:LuAG), corresponding to photon-quantum efficiencies of 1.78 and 1.54. Using an intracavity quartz birefringent filter, we achieve >220 nm of continuous tuning and reproducible two-color operation; in Tm:LuAG, the longest crystals impose a short-wavelength cutoff (below ∼1.92 μm), so shorter lengths are required for full spectral access. Passive Q-switching with a SESAM is strongest for 7 mm Tm:LuAG, producing 1.36 μs pulses with 1.2 W peak power. These results establish crystal-length selection rules for compact, red-pumped 2 μm sources balancing efficiency, tunability, and passive Q-switching.
A research on melting, energy storage, and entropy generation in a vertical shell-tube latent heat storage system with different fin models and laminar flow regimes
(Elsevier Masson s.r.l., 2026) Gürsoy, Emrehan
This numerical study investigates the melting time, energy storage, and second-law efficiency of a latent heat thermal energy storage (LHTES) system consisting of a vertical shell and tube heat exchanger using aluminium metal foam (MF) and fins with different geometries. RT58 paraffin wax phase change material (PCM) was used as the heat storage material, and heat input to the system was provided by hot water flowing through the inner tube in a laminar regime (Re = 1000 and 2000) and T inlet = 358 K. Rectangular, triangular, and parabolic fin models with the same total surface area were compared under different fin lengths. The analyses were carried out using the enthalpy-porosity approach and the Darcy–Brinkman–Forchheimer model. The results show that fin geometry and dimensions are decisive factors in PCM melting time, energy storage capacity, and entropy generation (EnG). While rectangular fins provided the shortest melting time, parabolic fins stood out with a more homogeneous melting profile and lower overall EnG performance. The best performance was obtained with the longest parabolic fin (P3) model. This model provided 4-19% lower thermal EnG compared to other geometries. Re = 2000 significantly shortened the full melting time of the PCM by increasing heat transfer compared to Re = 1000. The results show that the combined use of MF and fins in vertical shell and tube LHTES systems increases energy storage efficiency and reduces thermodynamic irreversibilities.
Twelve-month smoking cessation outcomes following immediate referral in people who smoke with chronic airway diseases: a randomized study
(BioMed Central Ltd, 2026) Karadoğan, Dilek; Telatar, Tahsin Gökhan; Kaya, İlknur; Atlı, Siahmet; Kabil, Neslihan Köse; Marım, Feride; Akgün, Metin
Background: Tobacco cessation support remains underutilized in routine care for patients with airway diseases such as asthma and COPD. In this multicenter randomized trial (NCT05764343, registration date: 2023-03-01), we previously reported that immediately scheduled appointments to smoking cessation clinics improved access and quit rates at 1-week and 3-month follow-ups. The present study evaluated whether these effects were sustained at 12 months. Methods: This prospective, parallel-arm, multicenter randomized trial included 397 adult people who smoke diagnosed with asthma, COPD, or bronchiectasis. Participants were allocated to either usual support (brief advice only) or immediate support (brief advice plus an appointment scheduled at a smoking cessation clinic). Smoking status was assessed by telephone at 12 months. Self-reported quitters were invited for exhaled carbon monoxide (CO) testing. The primary outcome was continuous abstinence at 12 months, analyzed on an intention-to-treat basis. Results: Of 397 randomized patients, 330 (83.1%) completed the 12-month follow-up, with similar loss to follow-up between groups. In the intention-to-treat analysis, the 12-month smoking cessation rate was significantly higher in the immediate support group compared with the usual support group (20.7% vs. 11.6%, p = 0.019). Among non-quitters, quit attempts, smoking cessation clinic admission, and pharmacotherapy use were significantly more common in the immediate support group (p < 0.05). Conclusion: Immediate scheduling of smoking cessation clinic appointments resulted in significantly higher 12-month quit rates compared to usual care. These findings support the integration of proactive referral strategies into routine management of patients with chronic airway diseases.
