TR-Dizin İndeksli Yayınlar Koleksiyonu
Permanent URI for this collectionhttps://hdl.handle.net/20.500.12573/396
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Article Theoretical Investigation of Steric Effects on the S1 Potential Energy Surface of O-Carborane Derivatives(Tubitak Scientific & Technological Research Council Turkey, 2023-01-01) Alkan, FahriTDDFT scan calculations were performed for s-carborane-anthracene derivatives (o-CB-X-Ant where X=-H,-CH3,-C2H5 and tert-butyl or-tBu) in order to understand the interplay between the steric effects, S1 potential energy surface (PES) and photophysical properties. The results show that all systems exhibit three local minima on the S1 PES, which correspond to the emissive LE and TICT state, along with the nonemissive CT state respectively. In the case of the unsubstituted system (o-CB-H-Ant), and-CH3 and-C2H5 substituted cases, S1 PES is predicted to be quite flat for certain conformations indicating that it is possible for these systems to reach the nonemissive CT state without a large energy penalty. In comparison, conformational pathways for the nonemissive CT state are predicted to be energetically unfavorable for o-CB-tBu-Ant as a result of both steric and electronic effects. These results provide a mechanism for the enhanced emission of cr-CB-fluorophore molecules with bulky ligands.Article Citation - WoS: 2Citation - Scopus: 2The Nexus of Leadership, Political Empowerment, and Social Mobilization: The Case of the July 15 Coup Attempt in Turkey(Seta Foundation, 2020-06-30) Donmez, Rasim Ozgur; Timur, Kasim; Lloyd, Fatma Armagan TekeThis study analyzes the mutually empowering relations between Turkish President Recep Tayyip Erdogan and his followers, and how Erdogan's charismatic leadership and image functioned to galvanize his followers on the night of July 15, 2016, when large numbers of them mobilized against the attempted coup. The article has three sections. The first is a theoretical discussion which sheds light on the concept and the underlying mechanisms of political empowerment and its effects on the relationships between leaders and followers. The second section evaluates Erdogan's characteristics and ruling style, which was instrumental in motivating resistance to the abortive coup. Finally, the third section analyzes the various means by which Erdogan was able to inspire the masses to mobilize against the armed junta through interviews and observations.Article Citation - WoS: 4Citation - Scopus: 5Noise-Assisted Multivariate Empirical Mode Decomposition Based Emotion Recognition(Istanbul Univ-Cerrahapasa, 2018-08-03) Ozel, Pinar; Akan, Aydin; Yilmaz, BulentEmotion state detection or emotion recognition cuts across different disciplines because of the many parameters that embrace the brain's complex neural structure, signal processing methods, and pattern recognition algorithms. Currently, in addition to classical time-frequency methods, emotional state data have been processed via data-driven methods such as empirical mode decomposition (EMD). Despite its various benefits, EMD has several drawbacks: it is intended for univariate data; it is prone to mode mixing; and the number of local extrema must be enough before the EMD process can begin. To overcome these problems, this study employs a multivariate EMD and its noise-assisted version in the emotional state classification of electroencephalogram signals. Emotion state detection or emotion recognition cuts across different disciplines because of the many parameters that embrace the brain's complex neural structure, signal processing methods, and pattern recognition algorithms. Currently, in addition to classical time-frequency methods, emotional state data have been processed via data-driven methods such as empirical mode decomposition (EMD). Despite its various benefits, EMD has several drawbacks: it is intended for univariate data; it is prone to mode mixing; and the number of local extrema must be enough before the EMD process can begin. To overcome these problems, this study employs a multivariate EMD and its noise-assisted version in the emotional state classification of electroencephalogram signals.Article Citation - WoS: 1Citation - Scopus: 2Metacognitive Monitoring and Mathematical Abilities: Cognitive Diagnostic Model and Signal Detection Theory Approach(Turkish Education Assoc, 2020-11-12) Basokcu, Oguz Tahsin; Guzel, Mehmet AkifBesides various in-class assessments, there exist some standardized assessment tools that are administered in several countries, such as PISA (Programme for International Student Assessment) and TIMMS (Trends in International Mathematics and Science Study). The questions' contents, type of responding, grading, and the analyses in these large-scale tests have been diversified in years. In this study, it was aimed to identify the abilities that are measured at PISA mathematics test in a single testing procedure and by utilizing the methods of analyses of Cognitive Diagnostic Model (CDM) as well as Signal Detection Theory (SDT), which have not been used so far in the assessment of these abilities. Therefore, a randomly selected sample of 6th-grade students (N=230) in Izmir was tested with a PISA-equivalent 12-item mathematics test, where the items are graded dichotomously (correct vs. incorrect). CDM estimates were calculated by using the Deterministic Input Noisy Output and Gate (DINA) Model. The participants were asked to report whether they thought they could solve the question correctly, guess even if they thought they could not solve the question, and then, rate their confidence levels on the correctness of their answers in turn so as to allow us to measure their "metacognitive monitoring performance" with the SDT method, which refers to the ability to differentiate correct and incorrect responses. In short, a better metacognitive monitoring performance was obtained by measuring how well once could differentiate their correct and incorrect responses with the observation of they prefer reporting and then giving high confidence levels to the actually correct responses and prefer passing to give an answer yet rate lower confidence levels to the actually incorrect responses given as pure guesses. The results showed that CDM fits well to the assessment of PISA test and those who were better at the ability of "reasoning and developing strategies" in particular among four possible abilities detected with CDM ("representing and communicating", "mathematization", "reasoning and developing strategies", "using symbolic and technical language") had also better metacognitive monitoring performance. The present study, therefore, contributes to the research that investigates what features the ability of better differentiating correct and incorrect responses are actually linked. Based on the results, it is suggested that a better metacognitive monitoring ability is linked to having a better ability of "reasoning and developing strategies" in particular. Additionally, it is suggested that measuring metacognitive monitoring performance at PISA -or even any other possible tests- with the SDT calculation method, that has a relatively straightforward testing procedure, may yield various estimates for the students' abilities measured at the test as well as their related higher-order abilities.Article Citation - WoS: 2Citation - Scopus: 3Magnetic Separation of Micro Beads and Cells on a Paper-Based Lateral Flow System(Gazi Univ, 2023-12-01) Farooqi, Muhammed Fuad; Icoz, KutayPaper based lateral flow systems are widely used biosensor platforms to detect biomolecules in a liquid sample. Proteins, bacteria, oligonucleotides, and nanoparticles were investigated in the literature. In this work we designed a magnetic platform including dual magnets and tested the flow of micron size immunomagnetic particles alone and when loaded with cells on two different types of papers. The prewetting conditions of the paper and the applied external magnetic field are the two dominant factors affecting the particle and cell transport in paper. The images recorded with a cell phone, or with a bright field optical microscope were analyzed to measure the flow of particles and cells. The effect of prewetting conditions and magnetic force were measured, and it was shown that in the worst case, minimum 90% of the introduced cells reached to the edge of the paper. The paper based magnetophoretic lateral flow systems can be used for cell assays.Article Citation - Scopus: 25Lyapunov Exponent Enhancement in Chaotic Maps With Uniform Distribution Modulo One Transformation(Akif AKGUL, 2022-03-30) Ablay, GünyazMost of the chaotic maps are not suitable for chaos-based cryptosystems due to their narrow chaotic parameter range and lacking of strong unpredictability. This work presents a nonlinear transformation approach for Lyapunov exponent enhancement and robust chaotification in discrete-time chaotic systems for generating highly independent and uniformly distributed random chaotic sequences. The outcome of the new chaotic systems can directly be used in random number and random bit generators without any post-processing algorithms for various information technology applications. The proposed Lyapunov exponent enhancement based chaotic maps are analyzed with Lyapunov exponents, bifurcation diagrams, entropy, correlation and some other statistical tests. The results show that excellent random features can be accomplished even with one-dimensional chaotic maps with the proposed approach. © 2023 Elsevier B.V., All rights reserved.Article Citation - WoS: 1Citation - Scopus: 2Investigation of the Interaction of Adipose-Derived Mesenchymal Stem Cells With Ε-Polycaprolactone and EGG White Scaffolds(Gazi Univ, 2023-12-01) Oztel, Olga N.; Yilmaz, Hilal; Isoglu, I. Alper; Allahverdiyev, AdilThe development of three-dimensional (3D) cell culture models is becoming increasingly important due to their numerous advantages over conventional monolayer culture. This study aimed to examine the interaction of adipose tissue-derived mesenchymal stem cells (AD-MSCs) with scaffolds composed of e-polycaprolactone (e-PCL) and egg white. In our study, e-PCL and egg white scaffolds were produced from their monomers by tin octoate catalyzed and heat polymerization, respectively. Characterization of e-PCL was carried out by Gel Permeation Chromatography (GPC), Fourier Transform Infrared Spectrophotometry (FTIR), Proton Nuclear Magnetic Resonance (H-NMR), Differential Scanning Calorimetry (DSC) and Scanning Electron Microscopy (SEM). AD-MSCs labeled with red fluorescent CellTracker CM-DiI were cultured on egg white and e-PCL scaffolds for 12 days. Cell viability was determined using 3-(4.5Dimethylthiazol-2yl)-2.5-diphenyltetrazolium bromide (MTT) and nitric oxide (NO) level was evaluated for toxicity. The results showed that the number of AD-MSCs in the egg white scaffold increased periodically for 12 days compared to the other groups. Although the number of ADMSCs in the e-PCL scaffold increased until day 6 of the culture, the number of cells started to decrease after day 6. These results were associated with the toxic effect of lactic acid release on cells resulting from the decomposition of e-PCL scaffolds through catabolic reactions. Therefore, these results indicated that the egg white scaffold enhanced and maintained cell adhesion and cell viability more than the e-Polycaprolactone scaffold and could be used as a scaffold in tissue engineering studies involving stem cells.Article Citation - Scopus: 2Investigation of Peroxidase-Like Activity of Flower-Shaped Nanobiocatalyst From Viburnum Opulus L. Extract on the Polymerization Reactions(Turkish Chemical Society, 2024-08-30) Kalayci, Berkant; Kaplan, Naime; Mirioglu, Muge; Dadi, Seyma; Öçsoy, Ismail; Göktürk, ErsenHere, we report the effects of peroxidase-mimicking activity of flower shaped hybrid nanobiocatalyst obtained from Viburnum-Opulus L. (Gilaburu) extract and Cu2+ ions on the polymerization of phenol and its derivatives (guaiacol and salicylic acid). The obtained nanoflowers exhibited quite high catalytic activity upon the polymerization of phenol and guaiacol. The yields and the number average molecular weights of the obtained polymers were significantly high. Due to solubility issue of salicylic acid in aqueous media, polymerization of salicylic acid resulted in very low yields. Free-horseradish peroxidase (HRP) enzyme is known to be losing its catalytic activity at 60 °C and above temperatures. However, the synthesized nanoflowers exhibited quite high catalytic activity even at 60 °C and above reaction temperatures. This provides notable benefits for reactions needed at high temperatures, and it is very important to use these kinds of nanobiocatalysts for both scientific studies and industrial applications. © 2024 Elsevier B.V., All rights reserved.Article Citation - WoS: 2Citation - Scopus: 3Investigation of Hydrogen Diffusion Profile of Different Metallic Materials for a Better Understanding of Hydrogen Embrittlement(Gazi Univ, 2023-12-01) Kapci, Mehmet Fazil; Bal, BurakIn this study, hydrogen diffusion profiles of different metallic materials were investigated. To model hydrogen diffusion, 1D and 2D mass diffusion models were prepared in MATLAB. Iron, nickel and titanium were selected as a material of choice to represent body-centered cubic, facecentered cubic, and hexagonal closed paced crystal structures, respectively. In addition, hydrogen back diffusion profiles were also modeled after certain baking times. Current results reveal that hydrogen diffusion depth depends on the microstructure, energy barrier model, temperature, and charging time. In addition, baking can help for back diffusion of hydrogen and can be utilized as hydrogen embrittlement prevention method. Since hydrogen diffusion is very crucial step to understand and evaluate hydrogen embrittlement, current set of results constitutes an important guideline for hydrogen diffusion calculations and ideal baking time for hydrogen back diffusion for different materials. Furthermore, these results can be used to evaluate hydrogen content inside the material over expensive and hard to find experimental facilities such as, thermal desorption spectroscopy.Article An Evaluation of the Rural Landscapes as Heritage From Habitus Perspective(Geleneksel Yayincilik Ltd Stl, 2024-03-19) Elagoz Timur, Bahar; Asiliskender, Burak; Timur, Bahar ElagözRural heritage areas consist of natural and built environments produced concerning local and traditional life practices, production -consumption habits, and intangible values of societies. This environment is created vernacularly using local materials and construction techniques due to the topographical features where it is built and is in contact with local users. For this reason, it is valuable to explain the meaning of vernacular architecture to understand its users and the habitus that emerges from it. Historical rural settlements, which have found their place in conservation theories over time, attract attention with their traditional and vernacular architecture.These areas, called "rural landscape as heritage" by definition developed by ICOMOS-IFLA, are accepted as a whole with their tangible and intangible components such as natural, archaeological, and architectural. Today, plenty of research is about integrated conservation issues of rural landscape heritages. The study, differently from theirs, plans to discuss the rural landscapes through habitus. It is possible to interpret the vernacular architecture produced in rural landscapes by understanding its user and the habitus in which it emerges. Moreover, there is a dynamic link between the traditional rural areas and the habitus of societies that produce and are produced by their daily lifestyles, traditions, collective memories, and histories. The habitus, which is always transformed, begins to adapt its environment to the change by this link. In this changing process, effects such as industrialization, technological developments, and globalization threaten rural landscapes to lose their authentic values. The first step in the conservation of rural landscapes lies in understanding these areas and their values and making change predictable. From this point of view, this study questions the role of habitus in the formation and life cycle of rural heritage. The research and the hypothesis created aim to contribute to the studies about sustainable living in rural landscapes by revealing the structuring effect of the habitus between the rural landscapes and their natural, built, and socio-cultural environments. In the study, the method developed from the literature to understand rural landscapes and their dynamics without studying the case is presented for use in rural landscape heritage conservation studies. Habitus connects the natural, tangible, and intangible components of rural landscapes by the balance it creates and contributes to the formation and maintenance of the spirit of place. In order to understand this balance and draw attention to holistic conservation approaches, the network of relations has been tried to be revealed in detail. Within the scope of the study, the definition of habitus was explained through the environment and practices, and its relationship with the rural landscape was conveyed through a single structure and settlement. The transition of living heritage is inevitable, but when it cannot be managed according to international regulations, the consequences will be the loss of rural heritage, which represents societies' traditional lifestyles. The proposed approach needs to be customized and re-established for each different rural landscape heritage site. Because each heritage site is unique and has its own conservation problems. It is critical to raise awareness about the effects of habitus change in rural landscapes and their management and to emphasize the importance of creating resilient rural heritage areas that can accompany change by preserving authentic values.