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Amino asit ile fonksiyonlandirilmiş fullerenoller: sentezi ve enzim taklidi ile organokataliz uygulamalari
No full textBuckminsterfullerene (C60) and its derivatives, particularly fullerenol, have gained attention due to their versatile applications. Fullerenol is hydrophilic and can be easily functionalized, making it a promising scaffold for catalysis. Amino acid-functionalized fullerenols tend to aggregate and form enzyme-like structures known as ‘fullerenzymes,’ which mimic enzymatic activity and serve as catalysts in organic reactions.
In the first part of this study, arginine functionalized fullerenol (F-Arg) was used as a biomimetic catalyst for LarE, the sulfur insertase of lactic acid racemase (Lar) from Lactobacillus plantarum. F-Arg facilitated the conversion of cysteine and nicotinic acid derivatives in buffer solution, mimicking the enzymatic transformation to dehydroalanine.
In the second part, histidine and serine functionalized fullerenol (F-HS) was coordinated with nickel ions and investigated as an esterase-mimic for acetylcholine detection in human serum. The F-HS-Ni sensor exhibited high sensitivity and selectivity, demonstrating its potential for biomedical applications.
In the third part, fullerenols and their amino acid derivatives were explored as organocatalysts. They efficiently catalyzed carbon dioxide fixation under mild conditions. Additionally, F-Arg served as basic catalysts in the Morita-Baylis-Hillman reaction and chromene synthesis. Fullerenols were also used as Brønsted acid catalysts in the Prins reaction.
These findings highlight the potential of fullerenol-based catalysts in biomimetic and organic transformations.Buckminsterfulleren (C60) ve türevleri, özellikle fullerenol, sahip olduğu geniş uygulama alanları nedeniyle dikkat çekmektedir. Fullerenol, hidrofilik yapısı ve kolay fonksiyonlandırılması sayesinde katalizör uygulamaları için uygun bir platform olarak görülmektedir. Amino asit ile fonksiyonlandırılmış fullerenoller, kendi kendine düzenlenerek enzim benzeri yapılar oluşturabilir ve ‘fullerenzimler’ olarak adlandırılan bu yapılar organik tepkimelerde katalizör görevi görebilir.
Bu çalışmanın ilk bölümünde, arjinin ile fonksiyonlandırılmış fullerenol (F-Arg), Lactobacillus plantarum kaynaklı laktik asit rasemazının (Lar) sülfür insertaz bileşeni LarE’nin biyomimetik bir katalizörü olarak kullanılmıştır. F-Arg, sistein ve nikotinik asit türevlerinin tampon çözelti içerisindeki dönüşümünü katalize ederek enzimatik olarak dehidroalanin oluşumunu taklit etmiştir.
İkinci bölümde, histidin ve serin ile fonksiyonlandırılmış fullerenol (F-HS) nikel iyonları ile koordine edilerek, insan serumunda asetilkolin tespiti için esteraz benzeri bir enzim modeli olarak incelenmiştir. F-HS-Ni sensörü yüksek hassasiyet ve seçicilik göstermiş, biyomedikal uygulamalar için potansiyelini ortaya koymuştur.
Üçüncü bölümde, fullerenoller ve amino asit türevleri organokatalizör olarak incelenmiştir. Ilımlı koşullarda karbon dioksit fiksasyonunda etkin bir katalizör olarak görev yapmıştır. Ayrıca, F-Arg, Morita-Baylis-Hillman tepkimesi ve kromen sentezinde bazik katalizör olarak değerlendirilmiştir. Fullerenoller ise Prins tepkimesinde Brønsted asidi katalizörü rolünü üstlenmiştir.
Bu bulgular, fullerenol bazlı katalizörlerin biyomimetik ve organik dönüşümlerdeki potansiyelini ortaya koymaktadır.Ph.D. - Doctoral ProgramTUBİTAK 118Z921GAP-103-2021-1063
Environmental effects of the Kakhovka Dam destruction by warfare in Ukraine
No full textThe use of water as a weapon in highly industrialized areas in the Russo-Ukrainian war has resulted in catastrophic economic and environmental damages. We analyze environmental effects caused by the military destruction of the Kakhovka Dam. We link field, remote sensing, and modeling data to demarcate the disaster's spatial-temporal scales and outline trends in reestablishment of damaged ecosystems. Although media attention has focused on the immediate impacts of flooding on society, politics, and the economy, our results show that toxic contamination within newly exposed sediments of the former reservoir bed poses a largely overlooked long-term threat to freshwater, estuarine, and marine ecosystems. The continued use of water as a weapon may lead to even greater risks for people and the environment
Pre-Alpine illitization ages from the Palaeozoic sequences of the Tauride Belt, Southern Türkiye: new data for a Late Palaeozoic event in northern Gondwana
No full textDue to the effects of the Alpine orogeny, it is extremely difficult to obtain age data for pre-Alpine geological events for northern Gondwana. This study aims to study the metamorphism in Precambrian (Ediacaran) metaclastic rocks of the Geyik Dağı unit and re-evaluate the geodynamic models of the northern Gondwana-margin based on the geochronology of illite diagenesis in the Late Silurian to Carboniferous shales of the Aladağ and Geyik Dağı units of the Taurides, in southern Türkiye. The average illitization (diagenesis) ages of ~ 275 Ma and ~ 165 Ma correspond to the periods of main unconformities between the Middle Carboniferous and the Late Permian and the Triassic and the Late Jurassic. The fossil records from below and above the unconformity plane between the Middle Carboniferous and the Late Permian indicate a gap of > 70 Ma. Mineralogical and organic matter reflectance data indicate a temperature difference of ~ 50°C between Permian and Carboniferous units indicating different thermal gradients below and above the hiatus. This thermal event coincides with the maximum burial depth resulting from the Palaeozoic subsidence curve of the Geyik Dağı Unit. Mineral and organic petrography-based thermal indicators indicate a pre-Alpine (Variscan) regional tectonic event, confirmed here for the first time by combined mineralogical, organic-petrographic, and isotopic age data. The new data may have the potential to re-evaluate geodynamic models of the northern Gondwana-margin during the Late Palaeozoic. The illitization ages associated with the Alpine metamorphism are ascribed to ophiolite emplacement during the Cretaceous and to tectonic events during the Eocene compressional period, which led to the present nappe structure of the Taurides
KATAR'DA GELİŞEN TOPLUMSAL TEHDİT ALGILARI VE GELİŞEN BALADNA KAVRAMI
No full textThis dissertation aims to examine the changing societal security perception in Qatar by testing a hypothesis: while migration-induced demographic imbalances and their associated existential threats created societal security concerns in Qatar akin to those in other Gulf States, the 2017 Gulf crisis marked a turning point. The crisis encouraged Qatar to adopt a more inclusive approach to societal security, expanding its core values beyond the traditional tribal framework toward an inclusive vision encapsulated by the term Baladna—a unifying symbol of national pride and collective identity. The dissertation also contributes to the theory of societal security by integrating Qatar’s evolving framework into the broader literature. Initially, societal concerns in Qatar were addressed within the context of state or political security, consistent with the Copenhagen School’s foundational understanding of security. During the 1990s and 2000s, Qatar’s perspective evolved with an emphasis on identity-related threats, focusing on migration and horizontal competition. However, the 2017 Gulf crisis marked a departure from this trajectory. While Qatar’s pre-2017 threat perceptions mirrored those of its neighbors, the crisis catalyzed the emergence of a distinct societal security perspective. This new framework, referred
to in this dissertation as Baladna, shifts focus from identity-oriented concerns to encompass life-giving functions and an all-hazards approach, paralleling the ‘New Nordic Understanding of Security’.Bu tez, Katar'da değişen toplumsal güvenlik incelemeyi amaçlamaktadır. Geçmişte göçün neden olduğu demografik dengesizlikler ve bu dengesizliklerle ilişkili varoluşsal tehditler, Katar'da diğer Körfez ülkelerine benzer toplumsal güvenlik endişeleri yaratmıştır. Ancak, 2017 Körfez Krizi bu duruma bir dönüm noktası olmuştur. Kriz, Katar'ın toplumsal güvenlik konusunda daha kapsayıcı bir yaklaşım benimsemesini teşvik etmiş ve temel değerlerini geleneksel kabile çerçevesinin ötesine taşıyarak, ulusal ve kolektif kimliğin birleştirici bir sembolü olan Baladna (Ülkemiz) terimiyle özetlenen kapsayıcı bir vizyona yöneltmiştir.
Teorik bir çerçevede ele alındığında ise: Başlangıçta Katar'daki toplumsal kaygılar, Kopenhag Okulu'nun ortaya koydugu temel güvenlik anlayışıyla tutarlı bir şekilde, devlet ya da siyasi güvenlik bağlamında ele alınmıştır. Ancak 1990'lı ve 2000'li yıllarda, Katar'ın bu bakış açısı kimlik odaklı tehditlere vurgu yaparak ve göç ile yatay rekabete odaklanarak gelişmiştir. Bununla birlikte, 2017 Körfez Krizi bu yörüngede bir sapmaya neden olmuştur. Katar'ın kriz öncesi tehdit algıları komşularınınkine benzerken, kriz sonrasında Baladna olarak adlandırılan ve "Yeni
İskandinav Güvenlik Anlayışı" ile paralellik gösteren yeni bir toplumsal güvenlik perspektifi ortaya çıkmıştır. Bu çerçeve, kimlik odaklı kaygılardan ziyade hayat veren işlevler ve tüm tehlikeleri kapsayan bir yaklaşımı merkezine almıştır.Ph.D. - Doctoral Progra
Nikel bazlı 718PLUS süperalaşım katılaşma davranışı ve mikroyapı oluşumu
No full textAlloy 718PlusTM is a Ni-based superalloy developed by ATI Allvac to increase Alloy 718 maximum service temperature by 55°C. Alloy 718 is widely used in aero gas turbine engines for its excellent performance at temperatures up to 649 °C. Alloy 718 stands out due to its favorable qualities, such as good forgeability, castability, and weldability. With advancements in gas turbine engine technology increasing the overall temperature capacity, the demand for cast static parts operable at higher temperatures is also evolving. Alloys like Rene 41 and Waspaloy can withstand higher temperatures than 649 °C; however, they present challenges in shaping, welding, and manufacturing. The Alloy 718 to 718PlusTM modification has made it a great alternative for applications requiring performance between 649°C and 760°C. 718Plus has already been used in forged form for gas turbine engines in the industry. This thesis explores the potential application of this alloy in cast form for static components. The effects of two different mould types—sand and metal—on the microstructure are compared. Alloy 718PlusTM was produced through induction melting under a protective argon atmosphere. Both revert 718 alloy and elemental raw materials were used in alloying 718PlusTM. Metal moulds produced finer dendritic structures. Homogenization of both castings showed different results. In sand casting, Laves phase dissolution is successfully achieved. However, in castings from metal moulds, Laves phases were not fully dissolved even after homogenization, showing brittle behavior. After solution treatment and aging, laves phase along the grain boundary were increased.718PlusTM Nikel bazlı süper alaşımı, ATI Allvac tarafından 718 alaşımının maksimum servis sıcaklığını 55°C artırmak için geliştirilmiştir. 718 alaşımı, 649 °C'ye kadar olan sıcaklıklarda mükemmel performansı nedeniyle aero gaz türbini motorlarında yaygın olarak kullanılır. Aynı zamanda 718 nikel alaşımı, iyi dövülebilirlik, dökülebilirlik ve kaynaklanabilirlik gibi olumlu nitelikleri nedeniyle de öne çıkmaktadır. Gaz türbini motorlarda türbin parçaları çalışma sıcaklıkları artırdıkça, daha yüksek sıcaklıklarda çalışabilen döküm parçalara olan talep de artmaktadır. Rene 41 ve Waspaloy gibi alaşımlar 649 °C'nin üzerinde sıcaklıklara dayanabilir; ancak şekillendirme, kaynaklama ve üretim süreçlerinde zorluklar ortaya çıkarmaktadır. 718 Alaşımı'nın 718Plus'a dönüştürülmesi, onu 649 °C ile 760 °C arasında performans gerektiren uygulamalar için mükemmel bir alternatif haline getirmiştir. 718Plus, gaz türbin motorlarında dövme formunda kullanılmaktadır. Bu tez, bu alaşımın döküm formunda statik bileşenler için potansiyel kullanımını araştırmayı amaçlamaktadır. İki farklı kalıp tipinin (kum kalıp ve metal kalıp) mikro yapı üzerindeki etkileri karşılaştırılmıştır. 718Plus alaşımı, koruyucu argon atmosferi altında indüksiyon ergitme yöntemiyle üretilmiştir. Alaşımlama sürecinde hem hurda 718 Alaşımı hem de saf hammaddeler kullanılmıştır. Metal kalıplar, daha ince dendritik yapılar üretmiştir. Her iki dökümün homojenizasyon ısıl işlemi sonucunda farklı davranış göstermiştir. Kum dökümde, Laves fazının çözünmesi başarıyla sağlanmıştır. Ancak metal kalıptan üretilen dökümlerde, homojenizasyon işlemine rağmen Laves fazları tamamen çözünmemiş ve kırılgan bir davranış sergilemiştir. Aynı dökümde çözeltiye alma ve yaşlandırma sonrasında tane sınırlarında lave fazları gözlemlenmiştir.M.S. - Master of Scienc
Self-determined motivation and driving styles as dependent on the perception of traffic climate by Turkish and Israeli drivers
No full textThe human factor is a prominent cause of traffic accidents. The formation of an individual's driving style has been found to be influenced by a variety of variables. In this study, the goal is to examine the moderating effects of the country (Israel and Türkiye) and the traffic climate on the relationship between the motivation for safe driving and driving styles. A Background Information Form, a Safe Driving Self-Regulation Questionnaire (SD-SRQ), the Traffic Climate Scale (TCS), and the Multidimensional Driving Style Inventory (MDSI) were used as instruments; data was collected from 471 Israeli and 400 Turkish participants. The contribution of the interaction between the motivation for safe driving and the traffic culture/climate in Israel and Türkiye on driving styles was examined by a moderated moderation analysis. The analysis showed that the two countries are differently impacted by traffic climate and safe driving motivation. The study's key finding is that while emotionally demanding traffic and autonomous forms of motivation and amotivation have an impact on the patient-careful driving style in Türkiye, traffic climate which is emotionally demanding and requires abilities and skills, together with controlled forms of motivation and amotivation have an impact on dissociative and anxious driving styles in Israel. Suggestions for further research as well as potential practical implications are discussed
Peace Education Program Adaptation: A Sustainable Way for Harmony
No full textPeace education has evolved over the past century, addressing various forms of violence and fostering values essential for harmonious coexistence. This research underscores the importance of addressing harmony and creating a peaceful environment through education utilizing Johan Galtung's framework on direct and structural violence. This study explores the adaptation of UNESCO's "Learning to Live Together" peace education program to meet the needs of fourth graders in refugee-receiving schools in Türkiye. The adapted program aims to equip individuals with skills for conflict resolution, empathy, and social justice, which are essential for both local and refugee students. A qualitative phenomenological approach was employed to capture the experiences of school components including local and refugee parents and students, teachers, school counselors, and vice principal, providing insights into the challenges and needs within this unique educational setting. As a result of the analysis of the semi-structured interviews with school components, three themes emerged: (1) Aggravating Factors for Unity, (2) Institutional Needs and Issues, and (3) Facilitative Factors for Unity. The needs analysis revealed significant aggravating factors for unity, such as language proficiency, socio-economic issues, and prejudice, necessitating a comprehensive, culturally sensitive educational intervention. However, factors like parental characteristics and a peaceful school environment can serve as facilitator factors. The study's findings informed the development of a 13-session peace education program for 4th graders tailored to the identified needs, emphasizing cultural recognition, conflict resolution, and empathy. This research highlights the critical role of peace education in promoting social cohesion and resilience, offering valuable insights for policymakers and educators in similar contexts
Endüstrinin kente entegrasyonu: temel tasarım stratejileri
No full textThe city and industry have been dynamic elements that have shaped each other throughout history, to the extent that their development and transformations cannot be considered separately. Despite this interactive relationship, environmental and spatial concerns led to the isolation of industry from the city, and production activities were relocated outside cities for a significant period. Currently, the necessity of industrial production in cities has been recognized, and the transformative impact of technological advancements on production processes and organizational structures has triggered the search for the re-integration of industry into the city. This situation has led to the requirement to reconfigure the spatial relationship between the city and industry, and such a tendency points to the necessity of re-evaluating the industry phenomenon in spatial planning and design and addressing it from a different perspective.
However, while economic arguments for industry and supporting policies have matured over time, spatial approaches and strategies to support production in cities are still in progress. In this context, this study addresses the issue of integrating industry into the city through a comprehensive review and spatial perspective. The study focuses on internationally produced research, projects, and practices in the context of the contemporary city-industry dynamic, aiming to explore how industry can be integrated into urban space. It explores the ways in which industry is combined with other urban functions, reveals integration typologies, and presents key design strategies in a strategic framework to ensure the integration of industry into the city.Kent ve endüstri, gelişimleri birbirinden ayrı düşünülemeyecek kadar iç içe geçmiş, tarihsel süreç boyunca birbirini şekillendiren dinamik unsurlar olmuştur. Ancak bu etkileşimli ilişkiye rağmen çevresel ve mekânsal kaygılar, endüstrinin kentten soyutlanmasına neden olmuş ve üretim faaliyetleri uzun yıllar boyunca kent dışına taşınmıştır. Günümüzde ise, endüstriyel üretimin kentlerde bulunmasının gerekliliği anlaşılmış ve teknolojik gelişmelerin üretim süreçleri ve organizasyon yapısı üzerindeki dönüştürücü etkisi, endüstrinin kentle yeniden bütünleşme arayışını tetiklemiştir. Bu durum ise kent ve endüstrinin mekânsal ilişkisinin yeniden kurgulaması gerekliliğini doğurmuştur ve böyle bir eğilim, mekânsal planlama ve tasarımda endüstri olgusunun yeniden değerlendirilmesi ve farklı bir bakış açısıyla ele alınması gerekliliğine işaret etmektedir.
Ancak, endüstriye yönelik ekonomik argümanlar ve bunu destekleyen politikalar zaman içinde olgunlaşırken, kentlerde üretimi desteklemeye yönelik mekânsal yaklaşımlar ve stratejiler henüz gelişim sürecindedir. Bu doğrultuda, bu çalışma endüstrinin kentle bütünleşmesine ilişkin sorunsalı kapsamlı bir inceleme ve mekansal perspektif ile ele almaktadır. Çalışma, günümüz kent-endüstri dinamiği bağlamında, endüstrinin kentle bütünleşebilmesi için uluslararası düzeyde geliştirilen araştırmalar, projeler ve uygulamalara odaklanmakta; endüstrinin diğer kentsel fonksiyonlarla bir araya getirilme biçimlerini inceleyerek entegrasyon tipolojilerini ortaya koymakta ve endüstrinin kentle bütünleşmesini sağlamak için temel tasarım stratejilerini stratejik bir çerçevede sunmaktadır.M.S. - Master of Scienc
Nonstationarity assessment in extreme temperatures and its association with antecedent soil moisture levels across diverse climate zones in Pakistan
No full textThis study investigates the nonstationary behavior of extreme temperatures in Pakistan across six diverse climatic zones over two distinct periods (1951–1985 and 1986–2020). The nonstationarity assessment is done by incorporating time and antecedent soil moisture (AMS) levels as nonstationarity covariates in Generalized Extreme Value (GEV) distribution. Results show significant intra-zonal, intra-seasonal, and intra-periodic variabilities in nonstationarity impacts on extreme temperatures. With few exceptions, maximum temperatures exhibited an increase in annual return levels particularly for second period while annual minimum temperature extreme gave mixed pattern during both periods. Seasonal analysis reveals notable intra-period variabilities, with most zones shows higher increase in maximum temperature return levels during second period up to + 2.3 °C and + 0.91 °C for spring and summer respectively. Conversely, minimum temperature analysis shows higher increase in return levels during spring (up to + 2.47 °C) and summer (up to + 2.02 °C) across most of the zones with decreased (up to -1.16 °C) return levels in central and eastern-western regions during winter. Except for two coastal zones, increased soil moisture levels were associated with significant reductions in maximum temperatures across most zones, with zonal average decrease in maximum temperature ranging from -0.01 °C to -0.05 °C per 1% increase in antecedent soil moisture. Positive association between minimum temperature and antecedent soil moisture has been found with zonal average range of + 0.002 °C to + 0.277 °C per 1% increase in antecedent soil moisture. The findings of this study have important implications for climate modeling, risk assessment, and adaptation strategies in the region for improved climate change assessment
On the maximally symmetric vacua of generic Lovelock gravities*
Full text linkWe survey elementary features of Lovelock gravity and its maximally symmetric vacuum solutions. The latter is solely determined by the real roots of a dimension-dependent polynomial. We also recover the static spherically symmetric (black hole) solutions of Lovelock gravity using Palais' symmetric criticality principle. We show how to linearize the generic field equations of Lovelock models about a given maximally symmetric vacuum, which turns out to factorize into the product of yet another dimension-dependent polynomial and the linearized Einstein tensor about the relevant background. We also describe how to compute conserved charges using linearized field equations along with the relevant background Killing isometries. We further describe and discuss the special vacua which are defined by the simultaneous vanishing of the aforementioned polynomials