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PMMA-based electrospun composite fibers for dye adsorption from water
No full textPoly (methyl methacrylate) (PMMA) and PMMA/poly (ethylene glycol) (PEG)-based composite fibers were produced using electrospinning technique with two different additives; halloysite nanotubes (HNTs) and boron phosphate (BPO4). The effect of the additives on the morphology, wettability and dye adsorption properties of electrospun fibers were investigated by Scanning Electron Microscopy (SEM), water contact angle measurement and UV-VIS spectrophotometry. The results of SEM analysis indicated that addition of PEG resulted in thinner average fiber diameter and beaded structure. Additionally, it was also observed that incorporating both HNT and BPO4to the PMMA solution caused increased fiber diameter which might be due to increased solution viscosity. For PMMA fibers containing 3 wt% HNT, the highest average diameter and water contact angle were measured as 2204 ± 302 nm and 110.29 ± 3.9°, respectively. The produced fibers were tested for the capability to adsorb methylene blue (MB) and methyl orange (MO) from aqueous solutions. Dye adsorption capacity of the samples increased by addition of HNT and BPO4. According to adsorption capacity results, PMMA/PEG/BPO4composite sample containing 5 wt% BPO4, with an adsorption capacity of 0.76 mg/g, was determined as adsorbent for kinetic and isotherm studies. The adsorption kinetics were well described by the pseudo-second-order model, and equilibrium data were correlated with the Langmuir model
Insight into Molecular Properties of Molasses by Means of 1H NMR Relaxation
Get PDFIn order to investigate the molecular properties of molasses, 1H spin-lattice and spin-spin relaxation experiments were performed at 18.56 MHz on a series of beet molasses (including their mixtures) and a series of cane molasses of different types and origins. The extensive data sets were thoroughly analyzed in search of characteristic relaxation features (markers) of the molasses. This revealed general relaxation characteristics of molasses, such as a linear trend of increasing relaxation rates with Brix degree (influenced to some extent by the presence of various additives, some of which are paramagnetic). In parallel, specific relaxation features, such as the bi-exponentiality of the spin-spin relaxation processes for some molasses, have been identified. The quantitative description and comparison of the relaxation parameters shows that although the type and origin of molasses cannot be unambiguously identified on the basis of the relaxation rates alone, the overall relaxation scenario described by a set of well-defined quantities provides a valuable insight for quality and authenticity testing of molasses. The NMR relaxation studies reveal differences between molasses at the level of molecular motion and arrangements that are not accessible by other methods
YAZILIM SİSTEMİ ARAŞTIRMA VE GELİŞTİRME PROJE SÜREÇLERİNİ İYİLEŞTİRMEYE YÖNELİK ZORLUK ODAKLI BİR YAKLAŞIM
No full textResearch and Development (R&D) projects are conducted across various sectors, particularly in automotive, energy, medical/pharmaceutical, and software industries. These projects present significant challenges due to the inherent complexity and uncertainty of the R&D lifecycle. This study focuses on software systems R&D projects, which play a critical role across nearly all industries today. The objectives of this study are to identify the challenges faced in software system R&D projects, make these challenges visible at the process level, and provide a guideline for improving project processes and addressing the challenges based on the Disciplined Agile Delivery framework. To achieve this, interviews were conducted with 12 individuals representing nine distinct roles across five different organizations. A total of 93 challenge instances were identified. Each challenge was thoroughly analyzed and mapped to the relevant processes defined in the ISO/IEC/IEEE 12207 Systems and Software Engineering – Software Lifecycle Processes standard. The challenges were then categorized into 27 unique first-level themes and 88 unique second-level categories. The process mapping results revealed that most challenges are associated with the Project Planning Process (20%), followed by the Acquisition Process (16%), the Stakeholder Needs and Requirements Identification Process (9%), and the Supply Process (8%). Finally, an improvement approach for software system R&D project processes was proposed, based on alternative solutions provided within the Disciplined Agile Delivery framework.Araştırma ve Geliştirme (Ar-Ge) projeleri, özellikle otomotiv, enerji, tıp/ilaç ve yazılım endüstrileri olmak üzere çeşitli sektörlerde yürütülmektedir. Bu projeler, Ar-Ge yaşam döngüsünün doğasında bulunan karmaşıklık ve belirsizlik nedeniyle önemli zorluklar ortaya koymaktadır. Bu çalışma, günümüzde neredeyse tüm sektörlerde kritik bir rol oynayan yazılım sistemi Ar-Ge projelerine odaklanmaktadır. Bu çalışmanın amacı, yazılım sistemi Ar-Ge projelerinde karşılaşılan zorlukları belirlemek, bu zorlukları süreç düzeyinde görünür kılmak ve bu projelerin zorluklarını önleyerek/çözerek yazılım sistemi Ar-Ge proje süreçlerini iyileştirmek için bir kılavuz sağlamaktır. Belirtilen amaçlara ulaşmak için, beş farklı kuruluşta dokuz farklı rolü temsil eden 12 kişiyle görüşmeler yapılmıştır. Toplam 93 zorluk örneği belirlenmiştir. Her zorluk ayrıntılı olarak analiz edilmiş ve ISO/IEC/IEEE 12207 Sistem ve Yazılım Mühendisliği Yazılım Yaşam Döngüsü Süreçleri standardında tanımlanan süreçlerle eşleştirilmiştir. Zorluklar daha sonra 27 benzersiz birinci seviye temaya ve 88 benzersiz ikinci seviye kategoriye ayrılmıştır. Zorlukların süreçlere haritalanması sonucunda, zorlukların çoğunun Proje Planlama Süreci ile ilişkili olduğunu (%20), ardından Satınalma Süreci(%16), Paydaş İhtiyaç ve Gereksinimlerinin Belirlenmesi Süreci (%9) ve Tedarik Süreci (%8) ile ilişkili olduğu ortaya konulmuştur. Son olarak, Disiplinli Çevik Teslimat metodu kapsamında sunulan alternatif çözümlere dayalı olarak, yazılım sistemi Ar-Ge proje süreçleri için bir iyileştirme yaklaşımı önerilmiştir.M.S. - Master of Scienc
360 derece kamera kullanan mobil robotlar için iç mekan topolojik navigasyon çerçevesinin geliştirilmesi
No full textThis thesis presents the development of an innovative topological navigation framework for mobile robots operating in indoor environments. A metric-free vision-based navigation system using 360-degree cameras is proposed to overcome the limitations of metric-based navigation systems. Equirectangular images are taken at each node by using a 360-degree camera mounted on the robot head. A topological map with nodes defined by equirectangular images is generated, and connections between nodes are determined using matching features. Feature extraction (ALIKEd) and matching (LightGlue) algorithms identify matching features. The 8-point algorithm with RANSAC estimates the heading vector and relative orientation between nodes. Heading vectors and relative orientations produce scale-free node coordinates, which are then validated with the reference floor plan. A graph search algorithm is utilized in the path-finding stage. Four routes across the map were driven in the normal direction and then in reverse, confirming that the proposed topological navigation algorithm supports reliable bidirectional travel. Also, another topological map consisting of fully connected 9 nodes with known positions was generated. Every node was used as a start once and as a goal for each of its eight neighbors, giving 72 start–goal trials with a mean position error of 0.32 m and an overall success rate of 88.9 %. A hand-mounted 360-degree camera performs vision-only triangulation of a specific object in the goal node. Two routes were traversed forward and reverse, confirming reliable bidirectional approach to the object. Also, the triangulation algorithm was validated in three indoor layouts, achieving a mean position error of 4.37 cm and a mean orientation error below 2.5 degrees. Overall, the results demonstrate that once the robot reaches its target pose, the manipulator can servo precisely to the object while remaining entirely within its 0.87 m horizontal workspace.Bu tez, kapalı ortamlarda çalışan mobil robotlar için yenilikçi bir topolojik navigasyon çerçevesinin geliştirilmesini sunmaktadır. Metrik-sensörlere ihtiyaç duymayan, 360 derece kameralarla çalışan bir görsel navigasyon sistemi önerilmektedir. Robotun başına monte edilen 360 derece kamera ile her düğüm noktasında eşdikdörtgen (equirectangular) görüntüler alınır. Bu görüntülerle düğümler tanımlanarak topolojik bir harita oluşturulur ve düğümler arasındaki bağlantılar, öznitelik çıkarma (ALIKEd) ve eşleştirme (LightGlue) algoritmalarıyla tespit edilen ortak özniteliklere göre belirlenir. 8-nokta algoritması ve RANSAC kullanılarak düğümler arası yön vektörleri ve bağıl yönelimler hesaplanır. Elde edilen bu yön vektörleri ve bağıl yönelimler, ölçeğe bağlı olmayan düğüm koordinatlarını üretir; bu koordinatlar, referans krokiye karşı doğrulanır. Yol bulma aşamasında grafik arama algoritması kullanılır. Harita üzerindeki dört rota, önce normal yönde sonra ters yönde sürülerek önerilen topolojik navigasyon algoritmasının çift yönlü güvenilirliği test edildi. Ayrıca, bilinen pozisyonlara sahip tam bağlı 9 düğümden oluşan başka bir topolojik harita oluşturuldu. Her düğüm bir kez başlangıç, her komşu düğüm ise bir kez hedef olarak seçilerek 72 başlangıç–hedef denemesi gerçekleştirildi; bu denemelerde ortalama 0.32 m pozisyon hatası ve %88.9 başarı oranı elde edildi. Robotun eline takılı ikinci bir 360 derece kamera ise yalnızca görsel verilerle hedef düğümdeki belirli bir nesnenin üçgenleme yoluyla konumunu belirler. İki rota ileri ve geri yönde sürülerek nesneye çift yönlü yaklaşma güvenilirliği doğrulandı. Ayrıca üç farklı iç mekân düzeninde yapılan testlerde ortalama 4.37 cm pozisyon hatası ve 2.5 derecenin altında yönelim hatası elde edildi. Tüm sonuçlar, robot hedef pozisyona ulaştıktan sonra manipülatörün 0.87 m yatay çalışma alanı içinde kalarak nesneye hassas bir şekilde yaklaşabildiğini göstermektedir.M.S. - Master of Scienc
3D structural controls of a high-enthalpy geothermal field in an extensional setting: the Kizildere geothermal field (Western Türkiye)
Get PDFThe Kızıldere Geothermal Field (KGF), situated at the eastern margin of the Büyük Menderes Graben, is the most productive high-enthalpy geothermal system in Türkiye, with reservoir temperatures exceeding 240 °C and an installed capacity of over 360 MW. Its heat is derived from crustal thinning, shallow Curie depths, and lithospheric extension related to the post‑Oligocene evolution of the Menderes Metamorphic Core Complex. This extensional tectonic setting produces high regional heat flow (up to 120 mW/m2) and steep geothermal gradients that favour deep fluid circulation. To resolve the structural and hydrogeological controls on this system, we combined detailed field mapping, paleostress and kinematic analyses, 76 boreholes (530–3882 m), and 3D geological and thermal modelling. The results reveal that fault architecture is the principal control on fluid flow and geothermal productivity. E–W‑striking high‑angle normal faults act as major recharge pathways for meteoric waters, whereas NE‑trending sub‑vertical transfer faults, particularly the Gebeler Fault, form vertical conduits that enable the rapid ascent of thermal fluids. Intersections of these faults create favourable zones, where fractured marbles, quartzites, and carbonate‑rich basin‑fill units function as reservoirs, sealed by gneisses, schists, and clay‑rich Miocene deposits. This study demonstrates that the interplay between fault geometry and lithology governs the exceptional productivity of the KGF. The insights gained provide a predictive framework for targeting high‑permeability zones, extensional geothermal systems in Western Anatolia, and similar tectonic settings worldwide
Osmanlı liman kentlerinde elitler ve konut: 18. yüzyıl Trabzon’undan mülk sahipliği yansımaları
No full textThis thesis examines property sales in eighteenth-century Trabzon, approaching them not only as economic processes but also as reflections of social relations, location preferences, and indicators of status. In this study, house sale deeds extracted from the court registers of Trabzon are used as primary sources. The study analyzes changes in housing prices over time, the relationships between buyers and sellers, and the configuration characteristics of the houses. Furthermore, a separate section focuses on the most expensive houses sold in the market. It has been determined that these houses are located in neighborhoods close to the city center or the port. As shown the value of real estate is shaped not only by physical size or structural features, but also by social environment, neighborhood location, and the profiles of the buyers and sellers. In this context, the analysis argues that in addition to economic capital, social position and symbolic indicators also played a decisive role in determining the property ownership of elites.On sekizinci yüzyılda Trabzon’da gerçekleşen konut satışlarını inceleyen bu tez çalışması, ev satışlarını yalnızca ekonomik işlemler olarak değil, aynı zamanda sosyal ilişkiler, mekânsal tercihler ve statü göstergeleri bağlamında ele almaktadır. Trabzon şer‘iyye sicillerinde bulunan ev satış kayıtlarının (mübaya’a hüccetleri) kaynak olarak kullanıldığı bu çalışmada konut fiyatlarının zaman içerisindeki değişimi, satıcı-alıcı arasındaki ilişkiler ve konutların fiziksel özellikleri aktarıldıktan sonra piyasa içindeki en yüksek bedelle satılan evler ayrı bir başlık altında incelenmiştir. Bu konutların şehir merkezlerine veya limana yakın mahallelerde yer aldığı tespit edilmiştir. Taşınmazların değeri yalnızca fiziksel büyüklük ya da yapısal değerlerle değil aynı zamanda sosyal çevre, mahalle konumu ve alıcı-satıcı profilleri ile şekillenmektedir. Bu bağlamda, tezde ekonomik sermayenin yanı sıra sosyal konumun ve sembolik göstergenin de belirleyici olduğu iddia edilmektedir.M.A. - Master of Art
Phenotypic plasticity including drug efflux drives reversible irinotecan resistance in LIM1215 colorectal cancer cells
No full textColorectal cancer (CRC) presents significant therapeutic challenges, particularly due to the development of resistance to standard chemotherapeutic agents such as irinotecan. In this study, we aimed to investigate the molecular and phenotypic mechanisms underlying irinotecan resistance in CRC using the LIM1215 cell line model. Transcriptomic analysis demonstrated that drug withdrawal induced major transcriptional reprogramming, characterized by downregulation of ABC transporters (ABCB1 and ABCG2), extracellular matrix-related genes, and markers of epithelial-to-mesenchymal transition (EMT), alongside reactivation of cell cycle pathways. Drug screening further indicated that resistant cells maintained under irinotecan pressure exhibited a multidrug-resistant phenotype, while withdrawn cells regained sensitivity, particularly to tyrosine kinase inhibitors. Supplementation with the efflux inhibitor Elacridar partially restored drug sensitivity in resistant cells, emphasizing the role of transporter-mediated efflux in maintaining resistance
Διπλωματία και Εκτόπιση: Επανεξέταζοντας την Ελληνοτουρκικνή Ανταλλαγή Πληθυσμών, 1922-1934
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Diffeomorphism invariance breaking in gravity and cosmological evolution
No full textDiffeomorphism invariance breaking has been investigated in the literature in several contexts, including emergent General Relativity (GR). If GR emerges from an underlying theory without diffeomorphism invariance, there may be small violations of this symmetry at low energies. Since such small violations should not cause instabilities in cosmological evolution, it is a suitable framework for examining such symmetry-breaking effects. In this paper, the cosmological evolution with broken diffeomorphism invariance is investigated in the (modified) FLRW spacetime in the effective theory framework. The GR Lagrangian is augmented with all diffeomorphism-breaking but Lorentz-invariant terms in the leading order, namely, those involving two derivatives. The magnitudes of (minor) violations are kept general modulo the conditions arising in the linearized theory. The analytic solutions of the scale factor in the full non-linear theory for the single-component universes are attempted; the radiation and vacuum solutions are found analytically, whereas the matter solution is worked out numerically since an analytic solution does not exist in the required form. It is observed that the solutions smoothly connect to those of GR in the limit of vanishing symmetry-breaking. The more realistic, two-component, and three-component universes are numerically studied, and no signs of singular behavior are observed: minor diffeomorphism-violating modifications to GR at the level of two derivatives do not cause instabilities in the basic cosmological evolution