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Article Citation - WoS: 2Citation - Scopus: 2Analysis of Optical Constants and Temperature-Dependent Absorption Edge of Gas0.75se0.25< Layered Crystals(Pergamon-elsevier Science Ltd, 2017) Isik, Mehmet; Gasanly, NizamiGaS0.75Se0.25 single crystals were optically characterized through transmission and reflection measurements in the wavelength range of 450-1000 nm. Derivative spectrophotometry analyses on temperature dependent transmittance spectra showed that band gap energies of the crystal increase from 239 eV (T=300 K) to 2.53 eV (T=10 K). Band gap at zero temperature, average phonon energy, electron phonon coupling parameter and rates of change of band gap energy with temperature were found from the temperature dependences of band gap energies under the light of different models reported in literature. Furthermore, the dispersion of room temperature refractive index was discussed in terms of single effective oscillator model. The refractive index dispersion parameters, namely oscillator and dispersion energies, zero-frequency refractive index, were determined as a result of analyses. (C) 2017 Elsevier Ltd. All rights reserved.Article Citation - WoS: 210Citation - Scopus: 259Impact of Cyclic Wetting-Drying on Swelling Behavior of Lime-Stabilized Soil(Pergamon-elsevier Science Ltd, 2007) Guney, Yucel; Sari, Dursun; Cetin, Murat; Tuncan, MustafaIn this study, the impact of cyclic wetting and drying on swelling behavior of lime-stabilized clayey soils has been investigated. Swelling potential and swelling pressure tests have been carried out on soil mixtures with various amounts of kaolinite-bentonite clays, and on a high plasticity clayey soil sample. The tests have been repeated after the addition of lime to the lime-treated samples in different preparation. In each cycle the tested samples were allowed air dry to their initial water content thus shrinking to their initial height, which is called 'partial shrinkage' method. The results showed that the initial beneficiary effect of lime stabilization was lost after the first cycle and the swelling potential increased at the subsequent cycles. On the other hand, the swelling potential and the swelling pressure of the untreated soil samples started decreasing after the first cycle and they reached equilibrium after the fourth cycle. (c) 2005 Elsevier Ltd. All rights reserved.Article Citation - WoS: 199Citation - Scopus: 195Existence and uniqueness of a common fixed point on partial metric spaces(Pergamon-elsevier Science Ltd, 2011) Abdeljawad, T.; Karapinar, E.; Tas, K.; Karapnar, E.In this work, a general form of the weak phi-contraction is considered on partial metric spaces, to get a common fixed point. It is shown that self-mappings S, T on a complete partial metric space X have a common fixed point if it is a generalized weak phi-contraction. (C) 2011 Elsevier Ltd. All rights reserved.Article Citation - WoS: 7Citation - Scopus: 8Some Remarks on Global Asymptotic Stability of Neural Networks With Constant Time Delay(Pergamon-elsevier Science Ltd, 2007) Singh, VimalAn elegant proof of a previously reported criterion for the uniqueness and global asymptotic stability of the equilibrium point of a class of neural networks with constant time delay is presented. The present proof yields some interesting observations. (c) 2005 Elsevier Ltd. All rights reserved.Article Citation - WoS: 11Citation - Scopus: 13A Low Band Gap Polymer Based on Selenophene and Benzobis (thiadiazole)(Pergamon-elsevier Science Ltd, 2017) Abdulrazzaq, Mohammed; Ozkut, Merve Icli; Gokce, Gurcan; Ertan, Salih; Tutuncu, Esra; Cihaner, AtillaA new derivative of benzobis(thiadiazole) based donor-acceptor-donor type monomers, namely 4,7-di (selenophen-2-yl)benzo[1,2-c;4,5-c']bis[1,2,5]thiadiazole (SeBTSe), was synthesized and its polymerization was carried out successfully via electrochemical polymerization in an electrolyte solution of 0.1 M tetrabutylammonium hexafluorophosphate dissolved in dichloromethane. The monomer SeBTSe is a deep red chromophore and it has four redox states: one oxidation, one neutral and two reduction states. The electrochemical behaviour of the corresponding polymer called PSeBTSe was studied by cyclic and differential pulse voltammetry. There is a good agreement between electrochemical (0.62-0.66 eV) and optical (0.63 eV) bandgaps of the polymer. Like the monomer, the ambipolar polymer has four redox states and electrochromic properties: gray beige at neutral state, smoky azurite at oxidized state, beige at first reduced state and dark beige at second reduced state. (C) 2017 Elsevier Ltd. All rights reserved.Article Citation - WoS: 137Citation - Scopus: 187Improving Programming Skills in Engineering Education Through Problem-Based Game Projects With Scratch(Pergamon-elsevier Science Ltd, 2018) Topalli, Damla; Cagiltay, Nergiz ErcilNowadays, programming skills are receiving widespread attention for different age groups alongside occupational education programs to better prepare individuals for their future careers. However, introducing programming concepts in an appropriate manner is a challenge in higher education. The main assumption of this study is that enhancing the classical introduction to programming courses through real-life problem-based game development with Scratch programming environment potentially improves the learners' programming skills and motivation. Accordingly, in this study, during one academic semester period, the Introduction to Programming course for engineering students is enriched up to a certain level through real-life game development projects with Scratch. The students are followed within a four-year period starting from freshman until their graduation. The progress of the students who have taken the Introduction to Programming course in enriched or classical form in the fourth year Senior-project course are evaluated. The results show that by slightly improving the course curriculum through real-life game development projects in the Scratch environment, students' performance on the graduation projects improved significantly. As a conclusion, game-based learning, problem-based learning, visual programming and projects are technologies that can potentially help learners to perform better in the introduction to programming course, in turn affecting their performances in projects.Article Citation - WoS: 7Citation - Scopus: 7Political Interest Across Cultures: the Role of Uncertainty Avoidance and Trust(Pergamon-elsevier Science Ltd, 2022) Kucukkomurler, Sanem; Ozkan, TurkerPrevious studies revealed a negative relationship between uncertainty avoidance tendencies and political interest at the country level. It implies that when there is a tendency to avoid uncertainties, citizens prefer not to be interested in politics. At the same time, there are findings in intergroup relations literature pointing to the intention to deal with uncertainties by participating in political activities (e.g., protests). We wonder whether a moderator, trust, impacts the relationship between uncertainty avoidance and political interest at the cultural level. The results demonstrated that (1) uncertainty is related to a decline in political interest, (2) trust has a moderator effect on the relationship between uncertainty avoidance and political interest, and (3) the moderation effect of trust is unique to the uncertainty avoidance dimension. These results revealed that trust has both enhancive and mitigative functions in the relationship between uncertainty avoidance and political interest.Article Citation - WoS: 70Citation - Scopus: 82The Effect of Uncertainty on Learning in Game-Like Environments(Pergamon-elsevier Science Ltd, 2013) Ozcelik, Erol; Cagiltay, Nergiz Ercil; Ozcelik, Nese SahinConsidering the role of games for educational purposes, there has an increase in interest among educators in applying strategies used in popular games to create more engaging learning environments. Learning is more fun and appealing in digital educational games and, as a result, it may become more effective. However, few research studies have been conducted to establish principles based on empirical research for designing engaging and entertaining games so as to improve learning. One of the essential characteristics of games that has been unexplored in the literature is the concept of uncertainty. This study examines the effect of uncertainty on learning outcomes. In order to better understand this effect on learning, a game-like learning tool was developed to teach a database concept in higher education programs of software engineering. The tool is designed in two versions: one including uncertainty and the other including no uncertainty. The experimental results of this study reveal that uncertainty enhances learning. Uncertainty is found to be positively associated with motivation. As motivation increases, participants tend to spend more time on answering the questions and to have higher accuracy in these questions. (C) 2013 Elsevier Ltd. All rights reserved.Article Citation - WoS: 5Citation - Scopus: 6Photoelectronic and Electrical Properties of Tl2ingas4< Layered Crystals(Pergamon-elsevier Science Ltd, 2007) Qasrawi, A. F.; Gasanly, N. M.Tl2InGaS4 layered crystals are studied through the dark electrical conductivity, space charge limited current and illumination- and temperature-dependent photoconductivity measurements in the temperature regions of 220-350 K, 300-400 K and 200-350 K, respectively. The space charge limited current measurements revealed the existence of a single discrete trapping level located at 0.44 eV. The dark electrical conductivity showed the existence of two energy levels of 0.32 eV and 0.60 eV being dominant above and below 300 K, respectively. The photoconductivity measurements reflected the existence of two other energy levels located at 0.28 eV and 0.19 eV at high and low temperatures, respectively. The photocurrent is observed to increase with increasing temperature up to a maximum temperature of 330 K. The illumination dependence of photoconductivity is found to exhibit supralinear recombination in all the studied temperature ranges. The change in recombination mechanism is attributed to exchange in the behavior of sensitizing and recombination centers. (C) 2006 Elsevier Ltd. All rights reserved.Article Citation - WoS: 44Citation - Scopus: 45A Novel Electrochromic and Fluorescent Polythienylpyrrole Bearing 1,1′-Bipyrrole(Pergamon-elsevier Science Ltd, 2009) Cihaner, Atilla; Mert, Olcay; Demir, Ayhan S.A novel conducting polymer was successfully synthesized via electropolymerization of 1-(1H-pyrrol-1-yl)-2,5-di(thiophen-2-yl)-1H-pyrrole. The electrochemical and electro-optical properties of the corresponding polymer, which was the first example of polymer containing 1,1'-bipyrrole units, were elaborated using electroanalytical and spectroscopic techniques. Cyclic voltammograms and electro-optical studies showed that the polymer has a stable and well-defined reversible redox process as well as electrochromic behavior. The processable polymer film also possessed a yellowish orange light emitter property. (C) 2008 Elsevier Ltd. All rights reserved.
