Sağlam, Özge
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Saglam, OEzge
Saglam, Özge
Saglam, Ozge
Saglam, Özge
Saglam, Ozge
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ozge.saglam@ieu.edu.tr
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05.10. Mechanical Engineering
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Documents
29
Citations
734
h-index
12
Documents
34
Citations
794
Scholarly Output
20
Articles
15
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33/814
Supervised MSc Theses
3
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0
WoS Citation Count
169
Scopus Citation Count
127
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7
Scopus h-index
6
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0
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7
WoS Citations per Publication
8.45
Scopus Citations per Publication
6.35
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9
Supervised Theses
3
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20 results
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Now showing 1 - 10 of 20
Article Citation - WoS: 4Citation - Scopus: 5Concentration Based Multicolor Upconversion Emission of Lanthanides Co -Doped Ruddlesden-Popper Type Layered Perovskites(Elsevier, 2020) Saglam, OzgeYb3+ ions initiated upconversion properties of Ruddlesden-Popper type layered materials were studied to elucidate the tunability of the visible emission under 980 nm excitation. The substitution of lanthanum ions in the host layer perovskites with different concentrations of Yb3+/Er3+ and Yb3+/Tm3+ as the sensitizer/activator pairs was performed via the solid-state procedure. The upconversion spectra of the samples have depicted that the materials relatively lower dopant concentrations of Yb3+/Er3+ have the green color, which was shifted to the red region due to both heavy activator and sensitizer concentrations because of the dominant F-4(9/2) -> I-4(15/2) transition rather than the H-2(11/2), S-4(3/2) -> I-4(15/2) transitions. The tunability of upconversion emission of Yb3+/ Tm3+ introduced materials was limited in the visible region compared to the Yb3+/Er3+ pair despite the fact that the wide variety of the lanthanide concentrations were studied and the layered materials were structured successfully. On the other hand, the first intense NIR emission was achieved for the layered perovskites co-doped with Yb3+/Tm3+ due to the H-3(4)-> H-3(6) relaxation.Article Citation - WoS: 7Citation - Scopus: 8Ag-Intercalation of Tm3+/Er3+ Co-Doped Layered Perovskites and Their Exfoliated 2d Nanosheets With an Enhanced Antibiofilm and Antibacterial Activity(Elsevier, 2022) Gunay, Bensu; Doger, Hilal; Karagonlar, Zeynep Firtina; Saglam, OzgeThere is a significant demand for antibiofilm and antimicrobial materials in the medical device industry. It is well established that Ag-based compounds have a high antimicrobial efficiency. Without being in a lattice, silver's antimicrobial action is mainly mediated by the release of Ag+ ions from the compound. These ions at high levels are toxic to most bacterial species. However, rapidly released Ag+ ions tend to aggregate and lose their anti-bacterial effect over time. Thus, utilizing a new approach for using silver as an antimicrobial agent based on imparting the antimicrobial action through contact, rather than releasing Ag+ ions could be beneficial. Here we report that Ag+ ions intercalation of Tm/Er co-doped layered perovskites and their 2D nanosheets exhibit antibacterial and antibiofilm activities against the human opportunistic pathogens Escherichia coli and Bacillus subtilis. Specifically, flocculation of nanosheets with Ag+ ions had efficient antibacterial and antibiofilm activity at 100 mu g/mL. In addition, the flocculated product demonstrated low in vitro cytotoxicity against the Huh7 hepatocellular carcinoma cell line and HEK 293 embryonic kidney cell line. Our results indicate that Ag-intercalated layered perovskites and the flocculation of the nanosheets hold great promise to be used for anti-microbial and antibiofilm purposes in biomedical engineering applications.Master Thesis 2d Perovskite Nanosheets for Multifunctional Device Fabrication and Biological Applications(İzmir Ekonomi Üniversitesi, 2021) Günay, Bensu; Sağlam, Özge; Karagonlar, Zeynep FırtınaBu tezin amaçları, frekans yükseltme özelliğine sahip nanolevhalar kullanılarak yapılandırılmış çok işlevli bir cihaz tasarımı ve biyolojik uygulamalar için iki boyutlu nanolevhaların biyouyumluluğunun araştırılmasıdır. K2Ln2Ti3O10 yapıda katmanlı perovskitler frekans yükseltme ile kırmızı ışıma elde edebilmek için farklı sitokiyometrik oranlarda Tm3+/Er3+ iyonları ile katkılandırılarak sentezlenmiştir. 2.5% Tm3+-20% Er3+ ile katkılı katmanlı malzemenin yanal boyutu 300 nm ile 2.5 µm arasında elde edilmiştir. Nanolevhaların kalınlığı 2-3 nm arasında belirlenmiştir ve tek nanolevhaların başarılı bir şekilde elde edildiği gösterilmiştir. Frekans yükseltme özelliğine sahip Tm3+/Yb3+ ve Er3+/Yb3+ ile katkılı nanolevhalar katman-katman tekniği ile 20 kez kaplanmıştır ve hazırlanan filmler sırasıyla 1G4 ›3H6 geçişi ile mavi ışıma ve 4S3/2›4I15/2 ve 2H11/2›4I15/2 geçişleri ile yeşil ışımalar göstermiştir. Öte yandan, Tm3+/Er3+ ortak katkılı nanolevha yapılı filmler, frekans yükseltme işlemi sırasında kırmızı ve yeşil emisyon sergilemiştir. Er3+/Yb3+ ortak katkılı nanolevhaların biriktirilmiş filmleri durumunda, yeşil ve kırmızı frekans yükseltme emisyonlarında iki foton süreçleri yer almıştır. 60 katman ile üretilen filmler ayrıca üç farklı nanolevhalar kullanılarak hazırlanmıştır. Film oluştururken nanolevhaların kombinasyonu CIE diagramında beyaz emisyon sergilemiştir. Ayrıca nanolevhaların sitotoksisitesi HepG2 ve HEK 293 hücre hatları kullanılarak analiz edilmiştir. HEK 293 hücre hattı için Tm3+/Er3+ katkılı katmanlı malzemenin toksisitesi %45,7 iken, nanolevhaların toksisitesi %73,6 olarak belirlenmiştir.Article Citation - WoS: 10Citation - Scopus: 11Upconversion Properties of Tm3+-Er3+ Co-Doped Layered Perovskites and In-Vitro Cytotoxicity of Their Exfoliated Nanomaterials(Elsevier, 2021) Gunay, Bensu; Sariyar, Ece; Unal, Ugur; Karagonlar, Zeynep Firtina; Saglam, OzgeThe upconversion behavior of Er3+/Tm3+ co-doped Ruddlesden-Popper type K(2)Ln(2)Ti(3)O(10) layered perovskites was investigated. The lanthanide pair was selected for achieving 980 nm-driven green, red, and NIR emission. The perovskites having different dopant compositions were synthesized by a conventional solid-state procedure by substitution of La3+ ions in the host lattice. Moreover, the single nanosheets having approximately 1.8 nm thickness and 2 mu m lateral size were obtained via chemical exfoliation. The non-doped and co-doped layered materials and the nanosheets derived from these materials were characterized by X-ray diffraction, Scanning Electron Microscopy, Atomic Force Microscopy and custom-made experimental set-up of upconversion emission spectroscopy. According to the XRD profiles, the perovskites had the layered orientation and water molecules in the interlayer domain because of their hygroscopic nature. The co-doped layered perovskites presented twophoton excited green and red emissions, identified as S-4(3/2) -> (4)I(15/2 )with H-2(11/2) -> (4)I(15/2 )and F-4(9/2) -> I-4(15/2) of the Er3+ transitions with a NIR emission. The intensity of red to green ratio emission of the materials increased with respect to the co-dopant concentration. The nanosheets' upconversion emission was weak in the visible region compared to their layered morphology. On the other hand, the NIR emission based on H-3(4) -> H-3(6) transition of the Tm3+ ions was preserved despite the acid and solvent treatments to break apart the layered orientation. MTT assay and Calcein/PI staining were conducted to evaluate cytotoxicity of non-doped and Er3+/Tm3+ co-doped K(2)Ln(2)Ti(3)O(10) perovskites and their exfoliated nanosheets on HEK 293 and HepG2 cell lines. Both assays indicated that although cell viability decreases with increasing concentration, good cell viability was observed at even 100 mu g/mL. In addition to their excellent luminescent and optical features, the nanomaterials also demonstrated low cytotoxicity increasing the potential for their use in laser-based biological applications.Article Citation - WoS: 12Tuning the Ease of Formation of On-Surface Metal-Adatom Coordination Polymers Featuring Diketones(Royal Soc Chemistry, 2018) Papageorgiou, Anthoula C.; Li, Jiang; Oh, Seung Cheol; Zhang, Bodong; Sağlam, Özge; Guo, Yuanyuan; Reichert, JoachimWe use pyrene-4,5,9,10-tetraketone molecules with substituents of varying bulkiness in the 2,7 positions to probe the generality and versatility of the previously reported on-surface coordination of two diketones with a single metal atom, leading to one-dimensional coordination polymers. Three different low index surfaces of group 11 metals (Cu, Ag and Au) are used to provide both the support and the metal atoms for metal-organic coordination. By real space visualisation with single molecule resolution employing scanning tunnelling microscopy we investigate the molecular self-assembly and show how this can be substantiated with the formation of metal-organic linear and cyclic oligomers, depending on the employed substrate.Article Citation - WoS: 16Dynamics of Spatially Confined Bisphenol a Trimers in a Unimolecular Network on Ag(111)(Amer Chemical Soc, 2016) Lloyd, Julian A.; Papageorgiou, Anthoula C.; Fischer, Sybille; Oh, Seung Cheol; Saglam, Ozge; Diller, Katharina; Duncan, David A.Bisphenol A (BPA) aggregates on Ag(111) shows a polymorphism between two supramolecular motifs leading to formation of distinct networks depending on thermal energy. With rising temperature a dimeric pairing scheme reversibly converts into a trimeric motif, which forms a hexagonal superstructure with complex dynamic characteristics. The trimeric arrangements notably organize spontaneously into a self-assembled one-component array with supramolecular BPA rotors embedded in a two-dimensional stator sublattice. By varying the temperature, the speed of the rotors can be controlled as monitored by direct visualization. A combination of scanning tunneling microscopy and dispersion corrected density-functional tight-binding (DFTB-vdW(surf)) based molecular modeling reveals the exact atomistic position of each molecule within the assembly as well as the driving force for the formation of the supramolecular rotors.Master Thesis 2d Oxide Dielectric Nanosheets Structured Nanofilms for Ultrathin, Flexible, Transparent Capacitor Fabrication and Biological Applications(İzmir Ekonomi Üniversitesi, 2024) Küçükcan, Begümnur; Sağlam, Özge; Gördeşli̇ Duatepe, Fatma PınarBu tezde, Dion-Jacobson (DJ) tipi KCa2NaNb4O13 katmanlı malzemeler katı hal yöntemi kullanılarak sentezlenmiştir. KCa2NaNb4O13 katmanlı malzemelerinin kimyasal pullandırma yöntemi ile 2.4 nm kalınlığında ve 3.5 µm yanal boyutlarında Ca2NaNb4O13 nanolevhaları içeren kolloidal solüsyonlar elde edilmiştir. Bu kolloidal solüsyonlar arasında TBA+:H+ oranı 1:16 olan solüsyon nanolevha üretimi için kullanılmıştır. Bu nanolevhalar, Langmuir-Blodgett (LB) kaplama yöntemi kullanılarak indiyum kalay-oksit – polietilen tereftalat (ITO-PET), Si, Ti/Au-Si, Ti/Au-cam ve ITO-cam alttaşları üzerine kaplanmıştır. Ek olarak, 10, 15 ve 20 katmanlı nanofilmler ITO-PET alttaşları üzerine kaplanmış ve optik litografi tekniği kullanılarak desenlenmiştir. Bu desenler, 75 nm kalınlığında ITO ile kaplanarak, 250 x 250 µm2' den 75 x 75 µm2' ye kadar değişen boyutlarda şeffaf ve esnek kapasitörler üretilmiştir. 10, 15 ve 20 katmanlı nanofilmlerini içeren kapasitörlerde, dielektrik katman sayısındaki artış, kaçak akım değerlerini azalttığı gözlemlenmiştir. Ayrıca, Si, Ti/Au-Si, Ti/Au-cam ve ITO-cam alttaşları üzerindeki nanofilmler, elektron demet litografisi (EBL) ile desenlenmiş ve 15/20 nm kalınlığında Ti/Au ile kaplanmıştır. Ti/Au-Si, Ti/Au-cam ve ITO-cam alttaşlar üzerinde de 20 x 20 µm2' den 250 x 250 nm2' ye kadar değişen boyutlarda Ti/Au elektrotlar da üretilmiştir. C-AFM ölçümleri ile bu elektrotların I-V analizleri yapılmıştır. Öte yandan, Ca2NaNb4O13 nanolevhaları ile üretilmiş nanofilmlerin Si ve ITO-PET alttaşları üzerindeki polar ve apolar yüzey gerilimleri, adezyon çalışmaları, yüzey termodinamiği temelli matematiksel modelleme ile hesaplanmıştır. Böylece, nanofilm ile ITO-PET arasındaki artan polar bağlanma, suda daha güçlü bir adezyona sebep olduğu tespit edilmiştir. Hem kaplanmamış hem de nanofilm kaplanmış Si ve ITO-PET alttaşlar üzerindeki bakteriyel biyofilm oluşumu, kristal viyole (CV) boyama yöntemi ile analiz edilmiştir.Article Flexible Transparent Nanocapacitors Based on High-k Perovskite Nanosheets(Wiley-v C H verlag Gmbh, 2025) Kucukcan, Begumnur; Saglam, OzgeThis work explores the integration of 2D Ca2NaNb4O13 - perovskite nanosheets into ultrathin dielectric films for flexible and transparent capacitors. Using Langmuir-Blodgett assembly technique, uniform nanofilms with precise thickness control are deposited on indium tin oxide-coated polyethylene terephthalate substrates. Capacitors fabricated with 10 and 20 layers of these nanosheets demonstrate stable dielectric performance and low leakage currents even under mechanical bending, offering capacitance densities of 0.42 and 0.27 mu F cm-2, respectively. Surface and interface characterization confirms the high-quality film formation and effective removal of exfoliation residues. Despite challenges arising from substrate roughness, the results validate the potential of oxide nanosheets for application in miniaturized, high-kappa flexible electronics.Article Citation - WoS: 21In Vacuo Porphyrin Metalation on Ag(111) Via Chemical Vapor Deposition of Ru-3(co)(12): Mechanistic Insights(Amer Chemical Soc, 2016) Papageorgiou, Anthoula C.; Diller, Katharina; Fischer, Sybille; Allegretti, Francesco; Klappenberger, Florian; Oh, Seung Cheol; Saglam, OzgePorphyrin molecules offer a very stable molecular environment for the incorporation of numerous metal ions inside their cavity, which enables a plethora of applications. The fabrication and characterization of surface confined metal organic architectures by employing porphyrins are of particular interest. Here, we report on a comprehensive study of chemical vapor deposition (CVD) of triruthenium dodecacarbonyl as metal precursor for the on-surface metalation of different porphyrin species with Ru under ultrahigh vacuum conditions. By employing synchrotron radiation X-ray photoelectron spectroscopy (XPS), near edge X-ray absorption fine structure (NEXAFS), and scanning tunneling microscopy (STM), we investigated the metalation process and particularly the role of the support: the close packed Ag(111) surface. It was found that the surface is active in the metalation process under the employed conditions: it decomposes the metal precursor and delivers metal centers to the porphyrin macrocycles. The generality of the metalation process is illustrated for tetraphenylporphyrin, its high temperature derivatives, and porphine.Article Citation - WoS: 11Citation - Scopus: 11Isomerism Control of Diethylstilbestrol by Metal Surface Induced O-H Cleavage(Royal Soc Chemistry, 2018) Oh, Seung Cheol; Lloyd, Julian A.; Fischer, Sybille; Saglam, OEzge; Papageorgiou, Anthoula C.; Diller, Katharina; Duncan, David A.Diethylstilbestrol (DES) is studied on Ag(111) and Cu(111) surfaces using X-ray photoelectron spectroscopy (XPS) and scanning tunnelling microscopy (STM). We find that DES molecules on the silver surface adsorb intact and adopt a trans-conformation. On the more reactive copper surface, O-H bond cleavage results in molecular adsorption in the cis-conformation, thus providing the means of obtaining different adsorption geometries. The difference in isomerism is reflected in the observed self-assemblies which exhibit room-temperature stability.
