Photonics / Fotonik
Permanent URI for this collectionhttps://hdl.handle.net/11147/2590
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Article Citation - WoS: 4Citation - Scopus: 4A Polymeric Copper Complex Based on a Pyrazole Derivative: Synthesis, Spectroscopic, X-Ray, and Biological Activity Studies(John Wiley and Sons Inc., 2024) Amin,M.A.; Diker,H.; Şahin,O.; Varlıklı, Canan; Soliman,A.A.A novel 1D coordination polymeric copper complex based on 4-(4′-nitrophenylhydrazono)-5-trifluoromethyl-2,4-dihydropyrazol-3-one was prepared and characterized spectroscopically and thermally and via X-ray crystallographic investigation. The prepared copper-based structure was proved to have a 1D coordination polymer. X-ray studies showed that the polymeric copper complex was of octahedral geometry, the ligand acted as a bidentate ligand, and the nitro group attached to the ligand acted as a bridging group. The cytotoxic activities of the copper polymer were evaluated including against MCF-7 cells (breast cancer cell line), HepG-2 cells (hepatocellular carcinoma), and HCT-116 cells (colon cancer cell line). The morphological alterations of the complex treated cells were investigated using an inverted microscope. The cell cycle and apoptosis were evaluated and reported. The copper polymer exhibited the best antitumor activity against HepG-2 cells (35.22 ± 4.80 μM) while also causing a decline in the G2/M phase and a remarkable enhancement in the early apoptosis. © 2024 John Wiley & Sons, Ltd.Preprint Electronic, Magnetic and Vibrational Properties of Single Layer Aluminum Oxide(2022) Özyurt, A. Kutay; Molavali, Deniz; Şahin, HasanThe structural, magnetic, vibrational and electronic properties of single layer aluminum oxide (AlO2) are investigated by performing state-of-the-art first-principles calculations. Total energy optimization and phonon calculations reveal that aluminum oxide forms a distorted octahedral structure (1T'-AlO2) in its single layer limit. It is also shown that surfaces of 1T'-AlO2 display magnetic behavior originating from the O atoms. While the ferromagnetic (FM) state is the most favorable magnetic order for 1T'-AlO2, transformation to a dynamically stable antiferromagnetic (AFM) state upon a slight distortion in the crystal structure is also possible. It is also shown that Raman activities (350-400 cm^-1) obtained from the vibrational spectrum can be utilized to distinguish the possible magnetic phases of the crystal structure. Electronically, both FM and the AFM phases are semiconductors with an indirect band gap and they can form a type-III vdW heterojunction with graphene-like ultra-thin materials. Moreover, it is predicted that presence of oxygen defects that inevitably occur during synthesis and production do not alter the magnetic state, even at high vacancy density. Apparently, ultra-thin 1T'-AlO2 with its stable crystal structure, semiconducting nature and robust magnetic state is a quite promising material for nanoscale device applications.Article Single Layer Res2h2: Stability, Raman Activity and Electronic Properties(Eskişehir Teknik Üniversitesi, 2018) Ünsal, Elif; Şahin, HasanIn this study, the structural, vibrational and electronic properties of the hydrogenated single layer of ReS2 are investigated byperforming the first principle calculations based on density functional theory. We found that the characteristic properties ofthe monolayer ReS2 can be manipulated upon the hydrogen functionalization. As the monolayer ReS2, the ReS2H2 hasdistorted 1T phase; however, the bonding in Re slab significantly varies with the hydrogenation. Our results demonstrate thatthe full-surface hydrogenation leads to an expansion in lattice and the Re4 tetramer-chains in the monolayer ReS2 areseparated into two dimers in the hydrogenated monolayer. It is calculated that the dynamically stable monolayer of ReS2H2has 26 Raman-active vibrational modes. Constant volume specific heat calculations are also performed and the resultsindicate that at high temperature, the monolayer ReS2 approaches to limit of 3R before the monolayer ReS2H2. By performingthe electronic band structure calculations, it is shown that when the ReS2 surface is fully hydrogenated, there occurs a directto indirect band gap transition and the semiconducting hydrogen-induced monolayer has a band gap of 0.74 eV.Patent Silicon-Based Emitter Compound(Espacenet, 2018)The present invention relates to emitter compounds E of formula or salts thereof based on a triazine core, substituted with at least one moiety of formula: and at least one donor moiety. Further, the present invention also refers to a light-emitting layer B comprising the emitter compound E and to an opto-electronic device OD comprising such light-emitting layer B. Moreover, the present invention relates to a method for generating light of a desired wavelength range by means of the opto-electronic device OD.Conference Object Citation - WoS: 3Citation - Scopus: 2Fabrication and Characterization of a Solution Processed Flexible Thermal Sensor by Using Chemically Synthesized Go and Rgo(Institute of Electrical and Electronics Engineers Inc., 2019) Bozkurt, Hakan; Diker, Halide; Varlıklı, CananGraphene oxide (GO) was reduced by ascorbic acid which is an environmental-friendly reductant and obtained sample was named as reduced GO (rGO). Stable dispersions of GO and rGO were prepared in N,N-Dimethylformamide (DMF). Compared to GO sample, rGO was determined to have more thermal stability, smaller sheet size and lower surface energy. GO and rGO dispersions were drop-casted on aluminum (Al) coated acetate substrate and used as thermal sensor. Fabricated sensors were tested from 25 °C to 150 °C. The sensors fabricated with GO, were not stabile against driven temperature changes. However, rGO ones, presented no thermal hysteresis effect after the first heating step. This sensor (Al/rGO/Al) acted like an NTC (Negative Temperature Coefficient) thermistor. The resistance of the rGO sensor was changed between 42 k? to 25 k? depending on the test temperature range (25 °C to 150 °C). Average beta value was calculated as 519.7649 K. © 2019 IEEE.Conference Object Bir Ameliyat Robotunun Denetimi için Basitleştirilmiş Dinamik Modeli(Otomatik Kontrol Türk Milli Komitesi, 2018) Ayit, Orhan; Yaşır, Abdullah; Vardarlı, Eren; Kiper, Gökhan; Dede, Mehmet İsmet CanBu çalışmanın temel konusu minimal invaziv tipi bir ameliyat olan endoskopik hipofiz tümörü ameliyatında kullanılan endoskopun hareket denetimi için geliştirilen robotik sistemdir. Geliştirilen sistemin bu bildiride ele alınan kısmı, ameliyat sırasında sadece ameliyat bölgesi içinde endoskopu cerrahın anlık isteklerine göre yönlendiren, aktif robot yapısıdır. Söz konusu robot uzak hareket merkezli, 3 serbestlik dereceli, paralel kinematik mimariye sahiptir. Bu çalışmada robotun denetimi için uygun görülen hesaplanmış tork yöntemi için gerekli robotun dinamik analizi sunulmaktadır. Denetim algoritmasının yüksek frekansta çalışabilmesi için dinamik denklemlerde yapılan basitleştirmeler ve bunun sonucunda elde edilen hesaplama zamanı sunulmaktadır.Book Part Citation - WoS: 6Citation - Scopus: 5Strain engineering of 2D materials(Springer Verlag, 2017) Cahangirov, Seymur; Şahin, Hasan; Le Lay, Guy; Rubio, AngelWhen bulk structures are thinned down to their monolayers, degree of orbital interactions, mechanical properties and electronic band dispersion of the crystal structure become highly sensitive to the amount of applied strain. The source of strain on the ultra-thin lattice structure can be (1) an external device or a flexible substrate that can stretch or compress the structure, (2) the lattice mismatch between the layer and neighboring layers or (3) stress induced by STM or AFM tip.Book Part Citation - WoS: 7Citation - Scopus: 10Germanene, Stanene and Other 2d Materials(Springer Verlag, 2017) Cahangirov, Seymur; Şahin, Hasan; Le Lay, Guy; Rubio, AngelGermanene and stanene (also sometimes written stannene or called tinene) are 2D materials composed of germanium and tin atoms respectively arranged in a honeycomb structure similarly to graphene and silicene. The atomic structure of freestanding germanene and stanene is buckled like in the case of silicene (see Figure 2.4DFT calculations (Kresse and Joubert, Phys Rev B 59:1758-1775, 1999) performed by projector augmented wave (PAW) method (BlÖchl, Phys Rev B 50:17953-17979, 1994) and adopting PBE functional (Perdew et al. Phys Rev Lett 77:3865-3868, 1996) result in a lattice constants 4.06 and 4.67Å and buckling heights of 0.69 and 0.85Å for germanene and stanene respectively.Book Part Citation - Scopus: 1Multilayer Silicene(Springer Verlag, 2017) Cahangirov, Seymur; Şahin, Hasan; Le Lay, Guy; Rubio, AngelSilicon does not have a naturally occurring layered allotrope like graphite. However, it is possible to grow monolayer silicene on substrates, as we have seen in Chap. 3. Extending this idea further, one may wonder whether it is possible to synthesize layered silicon structures by continuing the growth started as a monolayer silicene. In this chapter we discuss the experimental and theoretical works that are based on this idea of multilayer silicene growth.Book Part Citation - WoS: 1Citation - Scopus: 2Silicene on Ag Substrate(Springer Verlag, 2017) Cahangirov, Seymur; Şahin, Hasan; Le Lay, Guy; Rubio, AngelThe isolation of graphene sheets from its parent crystal graphite has given the kick to experimental research on its prototypical 2D elemental cousin, silicene (Brumfiel 2013). Unlike graphene, silicene lacks a layered parent material from which it could be derived by exfoliation, as mentioned in Chap. 2. Hence, the efforts of making the silicene dream a reality were focused on epitaxial growth of silicene on substrates. The first synthesis of epitaxial silicene on silver (111) (Vogt et al. 2012; Lin et al. 2012) and zirconium diboride templates (Fleurence et al. 2012) and next on an iridium (111) surface (Meng et al. 2013), has boosted research on other elemental group IV graphene-like materials, namely, germanene and stanene (Matthes et al. 2013; Xu et al. 2013). The boom is motivated by several new possibilities envisaged for future electronics, typically because of the anticipated very high mobilities for silicene and germanene (Ye et al. 2014), as well as potential optical applications (Matthes et al. 2013). It is also fuelled by their predicted robust 2D topological insulator characters (Liu et al. 2011; Ezawa 2012) and potential high temperature superconductor character (Chen et al. 2013; Zhang et al. 2015). One of the most promising candidates as a substrate is Ag because from the studies of the reverse system, where Ag atoms were deposited on silicon substrate, it was known that Ag and silicon make sharp interfaces without making silicide compounds (Le Lay 1983). Indeed, studies on synthesis and characterization of silicene is mainly focused on using Ag(111) as substrates and hence we think it is important to understand this particular system. In this chapter, we present the experimental and theoretical studies investigating the atomic and electronic structure of silicene on Ag substrates.