PubMed İndeksli Yayınlar Koleksiyonu / PubMed Indexed Publications Collection
Permanent URI for this collectionhttps://hdl.handle.net/11147/7645
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Article Citation - WoS: 3Citation - Scopus: 5Physically Unclonable Security Patterns Created by Electrospinning, and Authenticated by Two-Step Validation Method(IOP Publishing, 2022) Taşcıoğlu, Didem; Atçı, Arda; Sevim Ünlütürk, Seçil; Özçelik, SerdarCounterfeiting is a growing economic and social problem. For anticounterfeiting, random and inimitable droplet/fiber patterns were created by the electrospinning method as security tags that are detectable under UV light but invisible in daylight. To check the authenticity of the original security patterns created; images were collected with a simple smartphone microscope and a database of the recorded original patterns was created. The originality of the random patterns was checked by comparing them with the patterns recorded in the database. In addition, the spectral signature of the patterns in the droplet/fiber network was obtained with a simple and hand-held spectrometer. Thus, by reading the spectral signature from the pattern, the spectral information of the photoluminescent nanoparticles was verified and thus a second-step verification was established. In this way, anticounterfeiting technology that combines ink formula, unclonable security pattern creation and two-level verification is developed.Article Citation - WoS: 2Citation - Scopus: 2Mn2+ Ions Incorporated Into Znsxse1-X Colloidal Quantum Dots: Controlling Size and Composition of Nanoalloys and Regulating Magnetic Dipolar Interactions(IOP Publishing, 2021) Ünlütürk, Seçil Sevim; Akdoğan, Yaşar; Özçelik, SerdarA facile synthesis method is introduced how to prepare magnetically active ultraviolet emitting manganese ions incorporated into ZnSxSe1-x colloidal quantum dot (nanoalloy) at 110 degrees C in aqueous solutions. The reaction time is the main factor to control the hydrodynamic size from 3 to 10 nm and the precursor ratio is significant to tune the alloy composition. ZnS shell layer on the ZnSxSe1-x core was grown to passivate environmental effects. The nanoalloy has ultraviolet emission at 380 nm having a lifetime of 80 ns and 7% quantum yield. The incorporation of Mn2+ ions into the nanoalloys induced magnetic activity but did not modify the structure and photophysical properties of the nanoalloys. Colloidal and powdery samples were prepared and analyzed by electron paramagnetic resonance (EPR) spectroscopy. In the colloidal dispersions, EPR spectra showed hyperfine line splitting regardless of the Mn2+ ion fractions, up to 6%, indicating that Mn2+ ions incorporated into the nanoalloys were isolated. EPR signals of the powdery samples were broadened when the fraction of Mn2+ ions was higher than 0.1%. The EPR spectra were simulated to reveal the locations and interactions of Mn2+ ions. The simulations suggest that the Mn2+ ions are located on the nanoalloy surfaces. These findings infer that the magnetic dipolar interactions are regulated by the initial mole ratio of Mn/Zn and the physical state of the nanoalloys adjusted by preparation methods.Article Citation - WoS: 2Evaluation of Malassezia Species by Fourier Transform Infrared (ft-Ir) Spectroscopy(Ankara Microbiology Society, 2011) Ergin, Çağrı; Vuran, M. Emre; Gök, Yaşar; Özdemir, Durmuş; Karaarslan, Aydın; Kaleli, İlnur; Çon, Ahmet HilmiMalassezia species which are lipophilic exobasidiomycetes fungi, have been accepted as members of normal cutaneous flora as well as causative agent of certain skin diseases. In routine microbiology laboratory, species identification based on phenotypic characters may not yield identical results with taxonomic studies. Lipophilic and lipid-dependent Malassezia yeasts require lipid-enriched complex media. For this reason, Fourier transform infrared (FT-IR) spectroscopy analysis focused on lipid window may be useful for identification of Malassezia species. In this study, 10 different standard Malassezia species (M.dermatis CBS 9145, M.furfur CBS 7019, M.japonica CBS 9432, M.globosa CBS 7966, M.nana CBS 9561, M.obtusa CBS 7876, M.pachydermatis CBS 1879, M.slooffiae CBS 7956, M.sympodialis CBS 7222 and M.yamatoensis CBS 9725) which are human pathogens, have been analyzed by FT-IR spectroscopy following standard cultivation onto modified Dixon agar medium. Results showed that two main groups (M1; M.globosa, Robtusa, M.sympodialis, M.dermatis, M.pachydermatis vs, M2; M.furfur, M.japonica, M.nana, M.slooffiae, M.yamatoensis) were discriminated by whole spectra analysis. M.obtusa in M1 by 1686-1606 cm(-1) wavenumber ranges and M.japonicum in M2 by 2993-2812 cm(-1) wavenumber ranges were identified with low level discrimination power. Discriminatory areas for species differentiation of M1 members as M.sympodialis, M.globosa and M.pachydermatis and M2 members as M.furfur and M.yamatoensis could not be identified. Several spectral windows analysis results revealed that FT-IR spectroscopy was not sufficient for species identification of culture grown Malassezia species.Article Citation - WoS: 3Citation - Scopus: 4Evaluation of Multifunctional Hybrid Analogs for Stilbenes, Chalcones and Flavanones(Bentham Science Publishers, 2017) Çağır, Ali; Odacı, Burcu; Varol, Mehmet; Akçok, İsmail; Okur, Özgür; Koparal, Ayşe T.Aims: In this study, discovery of novel anticancer agents acting by more than one mechanism was aimed. Method: For this purpose, eleven previously synthesized simple-stilbene, chalcone, flavanone derivatives and 31 novel stilbene-fused chalcones and stilbene-fused flavanones were tested for their aromatase inhibition, anti-angiogenic and anti-proliferative properties in cancer (PC3, MCF-7) and healthy (HUVEC) cell lines. MTT cell viability assay was used to evaluate the anti-proliferative activities of the compounds. CYP19/MFC high-throughput screening kit (BD Biosciences, Oxford, UK) was used to search the aromatase inhibition properties and matrigel tube formation assay was applied to determine the anti-angiogenic activities. Results: Results indicate that the simple-chalcone and flavanone derivatives were more cytotoxic than the simple-stilbenes in the both cancer cell lines. In contrast, the simple-stilbene structures were much more effective at aromatase inhibition. The cytotoxicity profiles of stilbene-fused chalcones in cancer cells imply that these molecules mostly mimic the simple chalcone structures. On the other hand, flavanones lose their cytotoxic activities after becoming fused with stilbenes. Additionally, aromatase inhibition assays showed that stilbene-fused chalcones again do mimic the simple-chalcones but not simple-stilbenes and anti-angiogenic profiles of the tested molecules seem to be not related with stilbene fragments. Furthermore, stilbene-fused flavanones may mimic both simple-flavanones and simple-stilbenes depending upon the type and position of the substituent in their respective terminal aromatic rings.