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
Reply to the letter to the editor: two overlooked issues in hypertension management: risk thresholds and obesity integration
(Turkish Society of Cardiology, 2026) Özin, Bülent; Altun, Bülent; Cesur, Fazıl Mustafa; Ardıç, Cüneyt; Arıcı, Mustafa; Aydoğlu, Sinan; Düzenli, Mehmet Akif
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Structural, mechanical, electronic, and optical properties of SnBr2 and SnS2 as functional ceramic semiconductors for optoelectronic and energy applications
(Elsevier, 2026) Gueridi, Bachir; Slimani, Y.; Bouferrache, K.; Ghebouli, M.A.; Saidi, Samah; Yaylacı, Murat; Fatmi, M.
This work presents a comprehensive first-principles investigation of the structural, mechanical, electronic, and optical properties of layered SnBr₂ and SnS₂ compounds, with particular emphasis on their potential as functional ceramic semiconductors. Calculations were performed within the framework of density functional theory using the full-potential linearized augmented plane wave method as implemented in the Wien2k code. Structural optimization was carried out using the generalized gradient approximation, while the modified Becke–Johnson potential was employed to achieve improved accuracy in describing electronic and optical properties. The results confirm that both compounds crystallize in a stable hexagonal structure belonging to the P6₃/m space group and exhibit direct band-gap semiconducting behavior, with band gap values of 2.88 eV for SnBr₂ and 2.39 eV for SnS2. Elastic properties indicate mechanical stability, with SnBr₂ showing a ductile tendency and SnS₂ showing a brittle tendency according to the Pugh criterion SnS₂ shows higher mechanical rigidity and stronger bonding characteristics compared to SnBr₂, highlighting its suitability for ceramic-based functional applications. Optical analysis reveals absorption coefficients on the order of 10⁵ cm⁻¹ in the ultraviolet region, along with high refractive indices, indicating appreciable optical response and electronic polarizability. These properties, combined with their calculated band-gap values, suggest that SnBr₂ and SnS₂ are potential candidates for ceramic-based optoelectronic devices, UV/visible photodetectors, optical absorbers, and optical-coating applications. Overall, this study provides fundamental insights into the structure–property relationships of Sn-based layered compounds and highlights their potential as functional ceramic semiconductors for optoelectronic and optical-coating applications. This is supported by the clear effect of anion chemistry on the calculated properties, where SnS₂ shows stronger bonding and higher mechanical rigidity than SnBr2, while both compounds maintain dynamical stability, direct band gaps, and appreciable optical absorption.
Anogenital distance in patients with Klinefelter syndrome
(Korean Society for Reproductive Medicine, 2026) Uzun, Hakkı; Yiğit, Merve Hüner; Akça, Görkem; Orman, Erdem; Kaçan, Yakup; Sönmez, Berat
Objective: Anogenital distance (AGD) is a sexually dimorphic marker of genital development and fetal androgen activity. Shortened AGD has been linked to impaired male fertility. The distinct phenotypic and reproductive characteristics associated with Klinefelter syndrome (KS) may influence AGD. This study aimed to investigate AGD measurements in men with KS and evaluate their clinical significance. Methods: A case-control study was conducted involving 87 male participants categorized into three groups: normospermic (n=51), KS (n=18), and idiopathic non-obstructive azoospermia (iNOA; n=21). AGD was measured as the anoscrotal distance (AGDAS) using a digital caliper. Physical and hormonal evaluations, semen analyses, and karyotyping were performed. Group differences were analyzed using analysis of variance with posthoc testing, and Pearson correlations were calculated between AGD and clinical variables. Results: AGD measurements differed significantly between groups (F(2,87)=15.2, p<0.0005). AGD was longer in the normospermic group compared to the iNOA group (p<0.0005) and longer in the KS group than in the iNOA group (p=0.015). No significant difference was observed between normospermic and KS groups (p=0.153). Hormonal analyses showed lower testosterone and estradiol levels in KS patients compared to iNOA. Correlation analyses did not identify significant associations between AGD and clinical or hormonal parameters. Conclusion: AGD in men with KS is comparable to normospermic individuals and longer than in iNOA patients. In clinical assessments, the presence of small testes in individuals with AGD measurements similar to normospermic men may raise suspicion for KS.
Characterization of multilayer superhydrophobic surface for enhanced high voltage insulation
(Publishing House of the Romanian Academy, 2026) Alouache, Sara; Medjdoub, Abdellah; Tomakin, Murat
Superhydrophobic surfaces are widely used in electrical systems to repel moisture and enhance insulation performance. However, their exposure to environmental contaminants can degrade them over time. This study aims to characterize the properties of additional layers by analyzing their optical and structural characteristics. To evaluate the impact of multilayer deposition on their performance, several samples were prepared, then analyzed by FTIR, SEM, spectrometry, and contact angle measurement. The results indicate that increasing the number of layers enhances the structural uniformity, electrical stability, and optical transmission. These findings show the importance of multilayer structures in optimizing these surfaces, especially for electrical insulation.
Electronic, optical, thermoelectric and NMR properties of Rb₂XF₆ (X = Si, Pd) double perovskites for advanced energy recovery applications
(Springer, 2026) Alanazi, Faisal K.; Fatmi, M.; Ghebouli, M.A.; Bouferrache, K.; Alomairy, S.; Abualreish, Mustafa Jaipallah Abdelmageed; Yaylacı, Murat
We report a comprehensive first-principles investigation of the electronic, optical, and thermoelectric properties of Rb₂XF₆ (X = Si, Pd) double perovskites using density functional theory (DFT) and BoltzTraP2 transport calculations. The optimized structures crystallize in the cubic Fm3̄m phase with lattice parameters of 8.42 Å for Rb₂SiF₆ and 8.38 Å for Rb₂PdF₆, and bulk moduli of 45.2 and 52.8 GPa, confirming their mechanical and chemical stability. Electronic charge density analysis reveals that substituting Si with Pd redistributes electron density at the B-site, driving a transition from semiconducting behavior (indirect band gap of 2.84 eV for Rb₂SiF₆) to metallic character with partially filled Pd 4d states crossing the Fermi level. Optical calculations demonstrate strong ultraviolet absorption (α > 10⁵ cm⁻¹ at 4.5 eV) and refractive indices in the range 1.45–2.12, suggesting potential for UV photodetectors and optical coatings. Thermoelectric transport analysis shows a Seebeck coefficient of 180 µV/K at 300 K, increasing to 240 µV/K at 900 K for Rb₂SiF₆, alongside electrical conductivity values of 2.3 × 10¹⁸ (Ωms)⁻¹, indicating promising thermoelectric energy recovery capabilities. These findings highlight the tunability of Rb₂XF₆ compounds through chemical substitution and position them as promising candidates for dual-function UV optoelectronic and thermoelectric applications. Furthermore, multinuclear NMR experiments (⁸⁷Rb, ¹⁰⁵Pd/²⁹Si, and ¹⁹F) complement the theoretical results by confirming the high-symmetry Fm3̄m structure through the observation of narrow MAS peaks (FWHM ≈ 6 ppm) and characteristic static broadening, particularly for fluorine nuclei. This synergy between theory and experiment strengthens the reliability of the predicted local electronic environments and underscores the value of NMR as a probe for validating perovskite crystal structures.
