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Öğe Metamfetamin ve Amfetamin Bileşikleri Üzerine Sübstitüent Etkisinin Teorik Yöntemlerle İncelenmesi(Aksaray Üniversitesi, 2025) Aslan, Enis Can; Yıldız, Cem BurakBu tez çalışmasında, amfetamin ve metamfetamin yapılarının çeşitli analogları kuantum kimyasal yöntemler kullanılarak modellenmiş ve detaylı analizleri gerçekleştirilmiştir. Literatür değerlendirmesi sonucu uygun sonuçlar veren yöntemler titizlikle seçilmiş. İlgili yapıların yapıların optimizasyonları, frekans hesaplamaları, moleküler orbital analizleri ve spektroskopik karakterizasyonları uygun seviyelerde yapılmıştır. Yapıların en kararlı konformasyonları birer minimum olarak elde edilmiştir. Azot ve fosfor atomlarının yer aldığı farklı sübstitüe edilmiş türevler üzerinden HOMO-LUMO orbitallerinin ve moleküler elektrostatik potansiyel (MEP) dağılımlarının analizleri gerçekleştirilmiş. Böylelikle elektron yoğunluğu dağılımları ve moleküllerin reaktif bölgeleri belirlenmiştir. Diğer taraftan FT-IR, ¹H-NMR ve UV-Vis spektroskopileri için teorik veriler, deneysel literatür sonuçlarıyla karşılaştırılmış ve yüksek düzeyde uyum gözlemlenmiştir. FT-IR analizlerinde, fosfor içeren analoglarda C-P bağlarına ait karakteristik pikler daha düşük frekanslarda gözlemlenmiştir. ¹H-NMR hesaplamalarında ise yine azot ve fosfor varlığının kombinasyona bağlı olarak hidrojen atomlarının kimyasal kaymalarında belirgin etkiler yarattığı belirlenmiştir. TD-DFT hesaplamaları ile UV-Vis spektrumları değerlendirilmiş, aromatik halkalara ait absorpsiyon bantlarında yapısal değişimlere bağlı olarak dramatik olmasada çeşitli kaymalar gözlenmiştir. Sonuç olarak, bu çalışma ile bazı amfetamin ve metamfetamin benzeri bileşiklerin yapısal ve elektronik özelliklerinin teorik yöntemlerle başarılı bir şekilde modellenebildiği gösterilmiş. Bu yaklaşım, özellikle adli kimya ve farmasötik araştırmalar gibi alanlarda, yeni ve potansiyel olarak zararlı bileşiklerin deneysel sentezine gerek kalmadan ileri teoknoloji yöntemler kullanılarak (Kuantum kimyasal hesaplamalar) teorik düzeyde tanımlanmasına olanak sağlamakta ve kuantum kimyasal hesaplamaların öngörüsel gücünü vurgulamaktadır.Öğe Optical Characterization and Comparative Investigation of Cylindrical and Spherical Optical Microcavities(Aksaray Üniversitesi, 2025) Dündar, Gökçe; Anar, Kerem; Akçay, Namık; Eryürek, MustafaThis study focuses on the optical excitation and characterization of cylindrical and spherical microcavities using tapered optical fibers. Optical microcavity technologies offer significant potential for optical sensing applications requiring ultra-high sensitivity. In this study, the interaction mechanisms between tapered fiber structures and microcavities were examined in detail, and the properties of so-called “whispering gallery mode” (WGM) resonances were analyzed. Cylindrical microcavities provide a sensitive sensing platform against environmental changes due to their simple geometric structures, while spherical microcavities stand out with their symmetrical shapes and higher quality factors (Q-factors). These structures play a critical role in enhancing spectral resolution and achieving precise measurements in optical sensing. In the experimental setup, adiabatic tapering techniques were employed to fabricate tapered optical fibers, and the efficiency of fiber-microcavity interactions was optimized. This setup allowed for resolving WGMs spectrally making precise measurement of Q-factors possible. Larger free spectral ranges (FSR) were obtained with cylindrical microcavities, whereas spherical microcavities achieved extremely high Q-factors with denser mode spectra. The results revealed the critical impact of geometric properties, fabrication quality, and alignment precision of microcavities on optical performance. This study provides a significant foundation for the integration of tapered fiber-based microcavities into advanced sensing technologies. In the future, optimizing fabrication techniques and system geometries could further enhance the sensitivity and performance of microcavities.Öğe Optimization of Concrete Based on Scheffe’s Model Using Crushed Glass as Partial Replacement for Fine Aggregate(Aksaray Üniversitesi, 2025) Abbas, Bala Alhaji; Sulaimon, Nurudeen Adisa; Abubakar, Jibrin; Hamidu Jantabo, Uthman; Sodiq Alabi, Alao; Oluwayomi Akere, IsraelThis study developed a mathematical model for optimizing the 28-day compressive strength of concrete containing crushed glass and Bida Natural Gravel, based on Scheffe's simplex theory. Using a total of 30 mix ratios, 90 concrete cubes were cast to validate the model. Fifteen mix ratios derived from simplex lattice points were used to calculate model coefficients, while the remaining 15 pseudo-random mixes served as control points. The model’s predictions were statistically validated using the Fischer test, demonstrating adequacy with a 95 percent confidence level. Optimization via MATLAB revealed an ideal 28-day compressive strength of 36.83 MPa, corresponding to an optimal mix ratio—0.4739:1:0.6854:0.1952:1.7612 for water, cement, sand, crushed glass, and BNG. This model enables prediction of mix ratios for desired strengths of concrete containing 0 percent to 25 percent crushed glass.Öğe Recent Advances in the Study of Bulk Crystals: Copper Chalcogenides(Aksaray Üniversitesi, 2025) Akgün, Mehtap; Özışık, HacıSolid crystalline materials play a crucial role in a range of technological applications, from photovoltaics to thermoelectrics. Increasing the performance of these materials is important in terms of application efficiency. This review provides an overview of recent developments in the field, with a focus on photovoltaic materials, defect chemistry, and thermoelectric properties. Copper sulfide and selenides have advantages such as environmental friendliness, low cost and improved thermoelectric efficiency that set them apart from the competition. Special emphasis is placed on copper sulfides (Cu₂S) and selenides (Cu₂Se) due to their unique structural and electronic properties, making them promising candidates for sustainable energy applications. The manifestation of these copper chalcogens occurs within a variety of crystal structures, contingent on the liquid-like motion of the Cu⁺ ion within the crystal. In this review, the defective, deficiency and regular structures identified in recent years were also discussed.Öğe Carbon Nano-Onions in Biological Applications: Recent Progress and Future Directions(Aksaray Üniversitesi, 2025) Soylukan, Caner; Karaduman, Tuğçe Karaduman; Akyüz, LalehanCarbon nano-onions (CNOs), together with graphene and its derivatives, are one of the most interesting carbon nanostructures due to their peculiar chemical and physical properties. Made of a number of concentric fullerene layers, carbon-based structures have a peculiar design and assume the appearance of onion-like cages. Due to their excellent biocompatibility and safety, CNOs have low toxicity, high water dispersibility (due to surface functionalization), and high pharmacological efficacy. These properties render them highly appealing for applications such as drug delivery, sensing, imaging, tissue engineering, and therapeutic agents. While CNOs were discovered almost at the same time as other carbon nanomaterials (CNMs), their potential in biological applications remains largely unexplored. On the other hand, similar to other CNMs and fullerenes, CNOs play a crucial role as they represent carbon's ability to form diverse nanostructures with exceptional properties. This review aims to summarize recent studies on CNOs for biological applications, underlining the current achievements, possible opportunities, and challenges toward future development.
