Scopus İndeksli Yayınlar Koleksiyonu / Scopus Indexed Publications Collection
Permanent URI for this collectionhttps://hdl.handle.net/11147/7148
Browse
4 results
Search Results
Article Citation - WoS: 6Citation - Scopus: 6The Growth of Silver Nanostructures on Porous Silicon for Enhanced Photoluminescence: The Role of Agno3 Concentration and Deposition Time(EDP Sciences, 2019) Çetinel, Alper; Artunç, Nurcan; Tarhan, EnverSilver nanostructures were obtained by using the electrodeposition method on n-type porous silicon (PSi) under different deposition times and concentrations of AgNO3 solutions. The analyses of the structural and photoluminescence properties of PSi/Ag were studied by SEM, XRD and photoluminescence spectroscopy. SEM analysis showed that the shape and size of Ag nanostructures significantly depend on the deposition time and concentration. It was found that spherical nanoparticles and thin Ag dendrites were obtained in short deposition times at 1 and 5 mM AgNO3 concentrations, whereas, Ag complex dendrite nanostructures formed in long deposition times. It was also found that only micro-sized Ag particles were formed at 10 mM. XRD results revealed that the degree of crystallization increases with increasing concentration. Photoluminescence analysis showed that the deposition time and concentration of AgNO3 remarkably affect the PL intensity of PSi/Ag samples. We determined a PL enhancement of similar to 2.7 for the PSi/Ag deposited at 120 s for 1 mM AgNO3. The improved PL intensity of PSi/Ag nanostructures can be explained by the combination of quantum confinement and surface states. PL analyses also indicated that with increasing deposition time and AgNO3 concentrations, the PL intensity of PSi/Ag structures significantly decreases due to the auto-extinction phenomenon.Article Citation - WoS: 2Citation - Scopus: 2Comparison of Photocatalytic Properties of Tio2 Thin Films and Fibers(EDP Sciences, 2016) Özdemir, Mehtap; Kurt, Metin; Özyüzer, Lütfi; Aygün, GülnurEfficiency of solar panels degrades as a result of organic contamination such as airborne particles, bird droppings and leaves. Any foreign object on photovoltaic panels reduces the sunlight entering the absorbing surface of the solar panels. Since this leads to a major problem decreasing in energy production, solar panels should be cleaned. The self-cleaning method can be preferred. There are some methods to clean the surface of solar panels. Among the self-cleaning materials, TiO2 is the most preferable ones because of its powerful photocatalytic properties. In this study, photocatalytic TiO2 were produced in two different nanostructures: nanofibers and thin films. TiO2 nanofibers were successfully produced by electrospinning. TiO2 thin films were fabricated by reactive magnetron sputtering technique. Both TiO2 nanofiber and thin film structures were heat-treated to form TiO2 in anatase phase at 600 °C for 2 h in air. Then, they were evaluated by SEM analyses for morphology, X-ray diffraction (XRD) analyses for phase structures, X-ray photoelectron spectroscopy (XPS) for the chemical state and atomic concentration, and UV-spectrometer for photocatalytic performance. The results indicate that photocatalytic and transmittance properties of TiO2 thin films are better than those of nanofibers. Consequently, TiO2 based thin films exhibit better performance for solar cell applications due to the surface cleanliness.Article Citation - WoS: 3Citation - Scopus: 3Glycoalkaloid Isolation From Solanum Linnaeanum Berries(EDP Sciences, 2015) Gürbüz, Nergiz; Karabey, Fatih; Öztürk, Taylan Kurtuluş; Kılınç, Ali; Frary, Anne; Doğanlar, SamiGlycoalkaloids are plant secondary metabolites that can be both harmful and beneficial to human health. They cause gastroenteric symptoms, coma and even death at high concentrations. It is thought that glycoalkaloids are toxic to human health as a result of their effects on the nervous system and destruction of cell membranes. On the other hand, glycoalkaloids can be effective drugs. For example, solasodine is used to treat skin cancer and tomatidine is used in cancer chemotherapy. Solasodine is also used as a precursor of steroidal drugs. The goal of the work was to isolate and separate efficiently these similar compounds. Materials and methods. Glycoalkaloids from Solanum linnaeanum berries were isolated using column chromatography and confirmed via NMR spectroscopy and MS/MS spectrometry. Results and discussion. The chemical structures of glycoalkaloids are nearly identical. For example, solamargine differs from solasonine in having a methyl group instead of a hydroxyl group bound to the sugar residue of the compound. Thus, their molecular weight and polarity are quite similar. In this work, the process yielded 37.1 mg solasonine, 92.3 mg solasonine and solamargine mix and 56.2 mg solamargine from 81.67 g dried S. linnaeanum berries. Conclusion. Solanum linnaeanum berries are a good source of these glycoalkaloids and the developed protocol proved efficient for purification of solasonine and solamargine.Conference Object Citation - WoS: 1A Simple Case of D (x 2- Y 2) Pairing: Hubbard Ladder(EDP Sciences, 2012) Bulut, NejatWe study the strength and the temperature scale of the d(x 2-y2) pairing correlations in the Hubbard model on a ladder lattice using Quantum Monte Carlo (QMC) simulations. In particular, we present QMC results on the particle-particle interaction and the solution of the Bethe-Salpeter equation for the d(x2-y2)-wave BCS channel. These data show that there are strong d(x2-y2) pairing correlations in the Hubbard ladder for certain values of the model parameters. © Owned by the authors, published by EDP Sciences, 2012.