İstanbul Gedik Üniversitesi Kurumsal Akademik Arşivi
DSpace@Gedik, İstanbul Gedik 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 etkisini artırmak için telif haklarına uygun olarak Açık Erişime sunar.
Güncel Gönderiler
A new turn off flurecnloset NIR probe for hypochlorous acid and its applications
(Tubitak Scientific & Technological Research Council, 2025) Ibrahimova, Ayten; Önem, Ayşe Nur; Altun, Mehmet; Yeşil, Emin Ahmet; Baysal, Aslı; Saygın, Hasan; Soyocak, Ahu; Özyürek, Mustafa
Hypochlorous acid (HOCl) is a potent nonradical oxidant involved in various physiological processes, particularly within the human immune system. In this study, we introduce a novel, rapid, and highly efficient fluorometric method for the detection of HOCl. The method utilizes a near-infrared (NIR)-based fluorescent probe, NIR-QBH, which is characterized by its high sensitivity and chemical stability. NIR-QBH, containing olefinic C=C bonds, exhibits strong NIR emission at 660 nm (lambda ex = 618 nm). The detection mechanism relies on the oxidation of the C=C bond in the NIR-QBH structure by HOCl, resulting in the formation of non-fluorescent products. With a detection limit of 0.23 mu M, the probe demonstrates a fast response time of 4 min. Glutathione (GSH), an essential biothiol, was employed as a reference HOCl scavenger, and its HOCl scavenging activity was evaluated with an IC50 value of 8.97 mu M. Furthermore, the developed fluorometric assay was successfully applied for the detection of HOCl in fetal bovine serum (FBS) and aqueous solutions.
Use of transparent cover and elastic fixation band in patients with peripheral venous catheter: a comparison of microbiological colonisation
(MA Healthcare Ltd, 2025) Orhan, Büşra Nur; Göktaş, Sonay
Objective:The study was carried out to compare the effect of transparent covers and elastic fixation bands used in peripheral venous catheter fixation on microbiological colonisation in patients in intensive care. Method:This experimental randomised controlled study was conducted with patients treated in the Anesthesia and Reanimation Unit (an intensive care unit, ICU) of a training and research hospital in Istanbul between January 2019 and May 2020. Participants were divided into two equal groups: intervention: (catheters fixed with a transparent cover) and control (catheters fixed with an elastic fixation band) by the block randomisation method (CONSORT). After 72 hours, the catheters were removed aseptically and cultures were collected from the catheter tips. The roll plate technique was used and colony growth of >= 15 colony forming units was considered significant. The data of the study were collected using the 'Patient Information Form' and 'Catheter Follow-up and Result Form'. Results:A total of 60 patients were included in the study (30 in each group). It was found that the effect of the microbiological colony-forming microorganism species, and the area of catheter insertion on microbiological colonisation, were not statistically significantly different between the two groups (p>0.05). Conclusion:The findings of this study showed that both fixation methods can be used with effective nursing care in the treatment of patients in ICUs.
Multifunctional SnO2-@ doped glass fiber-reinforced concrete: improved microstructure, mechanical, dielectric, and energy storage characteristics
(Elsevier Ltd, 2025) Ramazanoğlu, Doğu; Subaşı, Azime; Musatat, Ahmad Badreddin; Demir, Ahmet; Subaşı, Serkan; Maraşlı, Muhammed
This study explores SnO₂-based hybrid composite (SnO₂-@) doped glass fiber-reinforced concrete (GFRC) for enhanced dielectric, energy storage, and mechanical performance. Microstructural analysis confirmed SnO₂-@ promotes ettringite and calcium silicate hydrate (C-S-H) formation, improving matrix integrity. Aged samples exhibited a 650 % increase in surface roughness (Ra) and over 200 % higher Leeb hardness, demonstrating durability. Dielectric spectroscopy revealed frequency-dependent tunability: 1 % SnO₂-@ achieved a peak dielectric constant (ε' = 130 at 10 kHz), shifting to ε' = 140 at 100 kHz for 2–3 % doping. AC conductivity surged by 60 %, correlating with SnO₂-@-induced interfacial polarization and charge mobility. Energy storage capacity improved significantly, attributed to optimized dipole alignment and reduced leakage currents. Color stability remained robust (ΔE* ≤ 2.8 post-aging), ensuring aesthetic viability. These results position SnO₂-@-doped GFRC as a multifunctional material for smart infrastructure, integrating structural resilience, adaptive dielectric properties, and energy storage potential for next-generation urban applications.
Experimental and optimization study of nanofluid utilized PVT systems with hydrocarbon based PCM: an energetic-exergetic approach
(Elsevier Ltd, 2025) Kurtoğlu Sontay, Kübra; Öğüt, Elif; Ustaoğlu, Abid; Özkan, Doğuş; Kurşuncu, Bilal
Cooling of photovoltaic thermal (PVT) systems is crucial for enhancing electrical efficiency by reducing the operating temperature of photovoltaic modules. Elevated temperatures negatively affect the performance of PV cells, leading to a decline in energy conversion efficiency. Photovoltaic thermal (PVT) systems, hybrid technologies that generate electricity and heat, are crucial for efficient energy conversion. This study uniquely explores the performance of a PVT system by integrating phase change materials (PCMs) and nanofluids in PVT systems combined with optimization analysis. By combining these advanced cooling methods, both electrical and thermal efficiencies are significantly optimized, demonstrating the potential for improved energy conversion in PVT systems. Within this scope, three identical systems–water-cooled, nanofluid-cooled, and a combination of nanofluid cooling with PCM- were analyzed regarding electrical, thermal, and exergy efficiencies. Identical panels were placed side by side and tested. Additionally, an optimization analysis has been conducted to enhance the performance of each panel by evaluating the thermal and electrical efficiency values obtained from experimental data based on system parameters and levels. In addition, thermogravimetric analysis and differential scanning calorimetry were conducted to determine the melting point of the Hydrocarbon-Based PCM. Compared with traditional methods, these analyses conducted in conjunction with the experimental study provide a more reliable basis for performance evaluation studies of PVT systems. The results of the experimental study showed that Nanofluid-Integrated PVT with Hydrocarbon-Based PCM achieved 11.7 %, 11.6 % and 10.6 % higher electrical efficiency, overall exergy and electrical exergy respectively, compared to the water-cooling method. Additionally, a 6.6-fold increase in thermal efficiency and a 4.4-fold increase in overall efficiency were observed. Similarly, compared to the nanofluid cooling method, this combination provided 4.9 %, 5.9-fold and 3.47 % improvements in the electrical, thermal and overall exergy efficiencies metrics. The results of the optimization analysis revealed that the combination of PCM and nanofluids ensures greater stability in electrical efficiency values under high-temperature differences. It was also observed that solar irradiance is the most influential parameter affecting efficiency. The obtained results demonstrate that the nanofluid-cooled system integrated with PCM has a significant impact on enhancing the performance of PVT systems. The combined use of nanofluid and PCM considerably improves all efficiency parameters.
The Role of RRA heat treatments on corrosion behaviour of AlSi10Mg produced by additive manufacturing
(Elsevier B.V., 2025) Özer, Gökhan; Tütük, İbrahim; Cingöz, Umut Can; Koç, Ebubekir; Karaaslan, Ahmet
In this study, AlSi10Mg samples were produced using the Powder Bed Laser Fusion (PBLF) method with standard parameters. Specimens were retrogression and re-aging (RRA) heat-treated at various conditions. The effects of the RRA heat treatments on the properties of PBLF parts were examined by microstructure, electrical conductivity, and electrochemical corrosion tests. Microstructural properties were investigated by scanning electron microscopy (SEM), X-ray diffraction (XRD), and energy-dispersive X-ray (EDS) analysis. The results showed that after RRA heat treatment, the electrical conductivity of the material decreased slightly, and the corrosion resistance increased.
