Fen Edebiyat Fakültesi

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  • Öge
    Redevelopment of Karaköy Harbor, Istanbul : need for a new planning approach in the midst of change
    (Elsevier, 2001) Öğüt Erbil, Aslı ; Erbil, Tansel ; https://orcid.org/0000-0003-3127-8905 ; 50161217900 ; Department of Sociology
    Following the examples in industrial countries, the old inner-city harbors in developing countries have also been subject to revitalization in the last decades. Karaköy Harbor in Istanbul is an example for undergoing transformation in a developing country, Turkey. This article depicts Karaköy Harbor's transformation and the related issues. The goal is to outline the character and condition of the harbor, present dilemmas for its future, while providing a different perspective on the revitalization of harbors both in Turkey and other countries. The research concludes that there is a need for a new planning approach that includes central–local government coordination and public participation.
  • Öge
    Social acceptance of the clean energy concept : exploring the clean energy understanding of Istanbul residents
    (Elsevier, 2011) Öğüt Erbil, Aslı ; https://orcid.org/0000-0003-3127-8905 ; Department of Sociology
    The energy issue is considered as one of the most important issues on the global agenda not only to meet the increasing energy needs but also for environmental protection and enhancement. Practices on utilizing renewable-clean energy sources and discussions related to these practices have been increasing worldwide. This paper's purpose is to provide empirical data for the deliberation of clean energy and its social acceptance by exploring Istanbul residents’ understanding on clean energy. The overall outcome of the conducted survey indicated that Istanbul residents have accepted the clean energy concept at the theoretical level. However, to carry out this acceptance, they should be provided more information and the changes to use them.
  • Öge
    Proceedings book of international workshop on theory of submanifolds
    (İstanbul Teknik Üniversitesi, 2017) Matematik Mühendisliği ; Mathematical Engineering ; Turgay, Nurettin Cenk ; Özkara Canfes, Elif ; Veken, Joeri Van Der ; Bejan, Cornelia-Livia
    Differential geometry is proving to be an increasingly powerful tool that improves its ties to other branches of mathematics such as analysis, topology, algebra, PDEs, and so on, as well as to theoretical physics research. The growing number of publications in the field of submanifolds was probably the main reason to organize the ”International Workshop on Theory of Submanifolds”, which took place at Istanbul Technical University, Turkey, from June 2 to June 4, 2016. One of the main features of the conference is the originality of its topic, being the only one focussing particularly on submanifold theory in the last few years. This is remarkable since submanifold theory is a very broad and omnipresent topic, going from surface theory in three-space, with applications in engineering and computer vision for example, to very abstract settings with high dimension and codimension, some of them appearing in modern physical theories. This volume, containing the proceedings of the above mentioned workshop, provides very recent results mainly on the theory of submanifolds, which the reader would be interested in getting acquainted with. The book is divided into three parts, each of them having a distinct editor. The first part contains surveys on submanifolds with certain properties, in particular on surfaces. Part two is the biggest one, and is devoted to the theory of submanifolds. The last part extends the main subject of the workshop toward some related topics, such as some geometrical structures which are extended from a manifold to the whole space containing the manifold (e.g. the total space of its cotangent bundle). The experience of the contributors to the Proceedings is illustrated by their publications in this field and the freshness of this conference was given mainly by the presence of many young mathematicians. The workshop was very successful, despite the critical period of this conference, where many participants had to cancel their participation for reasons beyond their control. All articles included here passed the usual referee process. Our warm thanks go to all those who contributed to this book by their work, to all participants of the workshop, to the referees of the Proceedings, to the host institution for organizing the conference and last but not least to our sponsors.
  • Öge
    Türkiye’de STS: Bilim ve Teknoloji Çalışmalarına Giriş
    (İstanbul Teknik Üniversitesi, 2020) İnsan ve Toplum Bilimleri Bölümü ; Turanlı, Aydan ; Aydınoğlu, Arsev Umur ; Şahinol, Melike
    Son 20 yılda başdöndürücü hızla gelişen ve etkisini tüm alanlarda gösteren bilgi ve iletişim teknolojilerindeki büyük ve hızlı dönüşümler, emek ve üretim süreçlerinden tüketim alışkanlıklarına kadar tüm yaşam biçimimizi dönüştürmekle kalmamış, bilim ve teknolojinin alışılmış düşünce kalıplarını zorlayan yepyeni soru ve sorunları da ortaya koymuştur. Bu sorunların tartışılması ve çözüm önerilerinin oluşturulması, yalnız teknik bilgiye sahip kişileri değil, bilim ve teknolojinin toplumsal, etik, felsefi, siyasal ve kültürel yanına odaklanan bütün paydaşları ilgilendirmektedir. Kitaptaki makaleler, bilim iletişiminden, makine etiğine, gıda bankalarından, tıbba, postfenomenolojiden, dijital bölünmeye, vatandaş biliminden, yapay zekâya kadar bilim ve teknolojinin yaşamsal konularını ağırlıklı olarak STS perspektifinden tartışır. Bu anlamda da, bilim ve teknoloji çalışmaları alanında Türkiye’de yayımlanan ilk kitap olma özelliğini taşımaktadır.
  • Öge
    Appraising science-policy interfaces in local climate change policymaking: Revealing policymakers’ insights from Izmir Development Agency, Turkey
    (Elsevier, 2022) Eroğlu, Mehmet ; Öğüt Erbil, Aslı ; https://orcid.org/0000-0003-3127-8905 ; Department of Sociology
    Developing knowledge-based and usable climate change policies requires establishing science-policy interfaces through which knowledge producers and policymakers cooperate. Current research reveals that co-production- based interfaces dominated neither by knowledge producers nor policymakers succeed in facilitating the transformation of knowledge into politics. From this point of view, this paper explores how Izmir Development Agency (IZKA), a regional development agency in Turkey, utilizes scientific knowledge and science-policy interfaces in its activities on climate change. Based on the analysis of agency documents and semi-structured interviews with experts from and outside IZKA, the findings indicate that IZKA thrives in integrating scientific knowledge on climate change in its activities drawing from multi-stakeholder and multi-level science-policy interfaces that have significant similarities with the co-production model. In these interfaces, international, national, regional, and local stakeholders share their resources, knowledge, and experience on climate change. Although legal, geographical, and demographic conditions also have an impact, the main reason behind IZKA’s success is the agency’s climate-focused vision that shapes decisions, strategies, organizational structure, and activities. In parallel to the indicated finding, this paper also discloses that the perspective of not prioritizing climate change and considering the potential benefits as only “co-benefit” does not yield results with the desired efficiency. Another finding is that even though the national government is the main actor on climate in Turkey, development agencies are capable of carrying out transformative activities in their regions, albeit limited.
  • Öge
    Bridging climate change science and policy through TMNs in Turkey : CoM as a boundary-object
    (Oxford University Press, 2022) Öğüt Erbil, Aslı ; Eroğlu, Mehmet ; Türk, Ebru Gönül ; https://orcid.org/0000-0003-3127-8905 ; Department of Sociology
    This paper qualitatively investigates one of the influential transnational municipal networks, Covenant of Mayors for Climate and Energy (CoM)’s position in three Turkish municipal governments in bridging the climate change science and climate change policy gap. In the last two decades, the importance of science-based policymaking for climate mitigation and adaptation and transnational municipal networks empowered by municipalities that guide city policies linked to international agreements has been recognized. In this paper, we argue that CoM has acted as a boundary-object in producing climate change policies and plans in Turkish municipal governments. However, CoM has done so to a certain extent; their effectiveness was limited due to the general atmosphere on climate change policies in Turkey. We substantiate this claim through a two-layer examination: a case-specific analysis of three municipalities and semi-structured interviews with thirteen experts in climate change policy-related issues.
  • Öge
    Zamana sığmayan lider : Haydar Aliyev'in yönetim ve devamlılık felsefesi
    (Azerbaycan Devlet İktisat Üniversitesi Bilim Kurulu, 2023) Kurbanov, Sadık ; Azerbaycan Millet Meclisi Doğal Kaynaklar, Enerji ve Ekoloji Komisyonu
    Bu eser, “Ulu Önder Haydar Aliyev”in siyaset felsefesi ve real politiğinin ana ilkeleri ve tezlerinin analizi, Aliyev araştırmalarının siyasi-felsefi temelinin oluşturulması konusunu ele almaktadır. Kitapta Haydar Aliyev’in hayatı, çizdiği siyasi portre, Sovyet ve bağımsızlık dönemlerindeki siyasi faaliyetleri, devlet yöneticiliği, iktisadi ve medeni kuruculuk yönü ve milli ideolojinin şekillendirilmesi alanlarındaki çalışmaları, ayrıca iç ve dış siyaseti incelenmektedir. Kitapta Haydar Aliyev siyasetinin felsefi mahiyeti, Azerbaycancılık ideolojisinin oluşturulması, bu ideolojinin dünyada yaşayan tüm Azerbaycanlıların mefkûresi haline dönüştürülmesi, hukuk devletinin ve sivil toplumun inşası, iç ve dış siyasetin birliği ve milli menfaatlere hizmet etmesi, hem ülkede hem dünyada barış ve huzurun tesisi gibi meseleler, felsefi ilkeler ve bilimsel-teorik tezler ilk kez bir araya toplanıp sistematik hale getirilmiştir. Kitap, Aliyev araştırmalarının siyasi ve felsefi yönünü, ayrıca siyaset felsefesinin bununla ilgili meselelerini derinlemesine ortaya koyması bakımından önem taşımaktadır.
  • Öge
    Polyether synthesis through reductive etherification reaction strategy
    (Wiley, 2023) Luleburgaz, Serter ; Tunca, Ümit ; Durmaz, Hakan ; orcid.org/0000-0002-3126-598X ; orcid.org/0000-0001-8767-6166 ; orcid.org/0000-0003-4710-2496 ; Kimya Bölümü
    The reductive etherification reaction (RER) of carbonyl groups (aldehydes or ketones) through silane as a reducing agent together with Bronsted or Lewis acid affords the synthesis of symmetrical and unsymmetrical ethers. This strategy is applied at the macromolecular level for the first time in 1993, and isophthalaldehyde is self-polymerized in the presence of triethylsilane (Et3SiH)/ tritylperchlorate (TrClO4) to yield polyethers with low to moderate molecular weights. Next, the polyethers with alternating structures are achieved by reacting isophthalaldehyde with bis(trimethylsilyl) ethers or diols as comonomers using reducing agent silane and Lewis acid. Moreover, in recent years, it is shown that polyether synthesis and post-polymerization modification (PPM) of polymers proceeds smoothly and effectively with the RER strategy in the presence of chlorodimethylsilane (CDMS), which acts as both a reducing agent and a Lewis acid.
  • Öge
    Mechanically robust shape-memory organohydrogels based on silk fibroin with organogel microinclusions of various sizes
    (Wiley, 2023) Bas, Yahya ; Okay, Oguz ; orcid.org/0000-0003-2717-4150 ; Kimya Bölümü
    Organohydrogels (OHGs) are soft materials with antagonistic hydrophilic and hydrophobic domains that have great interest for many different applications. This study presents the preparation of mechanically strong OHGs with shape-memory function by incorporating semicrystalline organo-microgels within the pores of silk fibroin (SF) scaffolds. In the first step, SF cryogels with various pore diameters between 26 ± 8 and 17 ± 4 µm are synthesized by cryogelation of aqueous SF solutions at concentrations between 5 and 20 w/v%. In the second step, the pores of SF scaffolds are filled with an organogel precursor solution containing n-octadecyl acrylate (C18A), acrylic acid, N,N'-methylene(bis)acrylamide, and an initiator. Once the free-radical polymerization took place inside the pores, OHGs containing organo-microgels of various sizes are obtained. The incorporation of the organogel component in the cryogels generates crystalline areas due to the side-by-side packed C18 side chains. OHGs' melting temperature and crystallinity level can be varied from 42 to 54 °C and from 2 to 16%, respectively. The stiffness of OHGs increases from 5.9 ± 0.5 to 18 ± 1 MPa with increasing SF concentration from 5 to 20 w/v%, which is attributed to the decreasing pore size of the cryogels and increasing thickness of the pore walls.
  • Öge
    Error analysis of the exponential wave integrator sine pseudo-spectral method for the higher-order Boussinesq equation
    (Springer, 2024) Çanak, Melih Cem ; Muslu, Gülçin M. ; 0009-0005-1699-5027 ; 0000-0003-2268-3992 ; Matematik Mühendisliği
    In this paper, we derive a new exponential wave integrator sine pseudo-spectral (EWI-SP) method for the higher-order Boussinesq equation involving the higher-order effects of dispersion. The method is fully-explicit and it has fourth order accuracy in time and spectral accuracy in space. We rigorously carry out error analysis and establish error bounds in the Sobolev spaces. The performance of the EWI-SP method is illustrated by examining the long-time evolution of the single solitary wave, single wave splitting, and head-on collision of solitary waves. Numerical experiments confirm the theoretical results.
  • Öge
    Modulating spectral response of raw photosynthetic pigments via ternary cadmium chalcogenide quantum dots : simultaneous enhancement at green spectrum and inhibition at UV region
    (Springer, 2024) Aykut, Sümeyye ; Ük, Nida ; Coşkun, İbrahim Yağız ; Şahin Keskin, Sultan ; Nar, Ilgın ; Trabzon, Levent ; Ünlü, Caner ; 0000-0001-7544-5360 ; 0000-0001-6626-8665 ; 0000-0002-1666-7438 ; 0000-0001-6606-5622 ; 0000-0003-2300-3071 ; 0000-0002-7323-3943 ; 0000-0002-0612-3111 ; Kimya Bölümü
    Photosynthesis relies on the absorption of sunlight by photosynthetic pigments (PPs) such as chlorophylls and carotenoids. While these pigments are outstanding at harvesting light, their natural structure restricts their ability to harvest light at specific wavelengths. In this study, Oleic acid-capped CdSeS and CdTeS ternary quantum dots (QDs) were synthesized using a novel two-phase synthesis method. Then, these QDs were used to interact with raw PPs, a mixture of chlorophylls and carotenoids isolated from spinach. Our findings revealed the following: (1) Interacting QDs with raw PPs effectively inhibited the chlorophyll fluorescence of the pigments upon excitation in UV light region (250–400 nm) without causing any damage to their structure. (2) By forming an interaction with QDs, the chlorophyll fluorescence of raw PPs could be induced through excitation with green-light spectrum. (3) The composition of the QDs played a fundamental role in their interaction with PPs. Our study demonstrated that the photophysical properties of isolated PPs could be modified by using cadmium-based QDs by preserving the structure of the pigments themselves.
  • Öge
    SH waves in a weakly inhomogeneous half space with a nonlinear thin layer coating
    (Springer, 2024) Ahmetolan, Semra ; Demirci, Ali ; Peker-Dobie, Ayşe ; Özdemir, Neşe ; 0000-0003-1003-7918 ; 0000-0002-5228-7694 ; 0000-0002-9144-5691 ; Matematik Mühendisliği
    We investigate the self-modulation of Love waves propagating in a nonlinear half-space covered by a nonlinear layer. We assume that the constituent material of the layer is nonlinear, homogeneous, isotropic, compressible, and hyperelastic, whereas for the half-space, it is nonlinear, heterogeneous, compressible and a different hyperelastic material. By employing the nonlinear thin layer approximation, the problem of wave propagation in a layered half-space is reduced to the one for a nonlinear heterogeneous half-space with a modified nonlinear homogeneous boundary condition on the top surface. This new problem is analyzed by a relevant perturbation method, and a nonlinear Schrödinger (NLS) equation defining the self-modulation of waves asymptotically is obtained. The dispersion relation is derived for different heterogeneous properties of the half-space and the thin layer. Then the results of the thin layer approximation are compared with the ones for the finite layer obtained in Teymur et al. (Int J Eng Sci 85:150–162, 2014). The solitary solutions of the derived NLS equation are obtained for selected real material models. It has been discussed how these solutions are influenced by the heterogeneity of the semi-infinite space.
  • Öge
    Various optimized machine learning techniques to predict agricultural commodity prices
    (Springer, 2024) Sarı, Mustafa ; Duran, Serbay ; Kutlu, Hüseyin ; Güloğlu, Bülent ; Atik, Zehra ; Matematik Mühendisliği
    Recent increases in global food demand have made this research and, therefore, the prediction of agricultural commodity prices, almost imperative. The aim of this paper is to build efficient artificial intelligence methods to effectively forecast commodity prices in light of these global events. Using three separate, well-structured models, the commodity prices of eleven major agricultural commodities that have recently caused crises around the world have been predicted. In achieving its objective, this paper proposes a novel forecasting model for agricultural commodity prices using the extreme learning machine technique optimized with the genetic algorithm. In predicting the eleven commodities, the proposed model, the extreme learning machine with the genetic algorithm, outperforms the model formed by the combination of long short-term memory with the genetic algorithm and the autoregressive integrated moving average model. Despite the fluctuations and changes in agricultural commodity prices in 2022, the extreme learning machine with the genetic algorithm model described in this study successfully predicts both qualitative and quantitative behavior in such a large number of commodities and over such a long period of time for the first time. It is expected that these predictions will provide benefits for the effective management, direction and, if necessary, restructuring of agricultural policies by providing food requirements that adapt to the dynamic structure of the countries.
  • Öge
    Elemental composition of household dusts extracted in simulated body fluids and their impact on culturable pathogenic bacteria responses
    (Springer, 2024) Baysal, Aslı ; Zora, Sevilay ; Saygın, Hasan ; 0000-0002-0178-7808 ; 0000-0002-6534-0538 ; 0000-0003-2479-7635 ; Kimya Bölümü
    In the last decade, a great deal of research has focused on the determination of potential toxic elements by total concentration and identification the microorganisms in dust. However, determining bio-relevant (e.g., inhalable) forms of elements instead of total contents in acids is necessary for human health. Moreover, examination of the behavior of microorganism under these bio-relevant conditions and revealing the interaction between elements and pathogens is vital and necessary for deeper understanding. However, previous studies have ignored these topics. Therefore, the present study aimed to (i) investigate elements in household dusts extracted in simulated lung fluids, (ii) examine the total concentration of culturable bacteria and their biochemical responses with exposure to bio-fractions of household dusts, and (iii) assess their relations and risks using the model approaches by inhalation. Here, settled dusts were collected in 25 houses, and extracted in four simulated body fluids to determine bio-fractions of elements. Moreover, total count of potentially pathogenic and heterotrophic bacteria, and four clinically important culturable pathogens were incubated in the presence of household-dusts extracted in simulated body fluids. The activity, biofilm, biochemical and oxidative responses of pathogens were measured following household-dust exposures. Afterward, the relationship between elements and pathogen responses were evaluated, and model and derived approaches were used for risk assessments of elements and pathogens. The higher daily intake of elements obtained in artificial lysosomal fluid fraction of household dust mimicking the inflammatory condition compared to other body fluids. Moreover, bacterial responses were mainly influenced from bio-fractions of household dusts and their elemental contents.
  • Öge
    A novel image denoising technique with Caputo type space–time fractional operators
    (Springer, 2024) Tanrıöver, Evren ; Kiriş, Ahmet ; Tunga, Burcu ; Tunga, M. Alper ; 0000-0003-4098-3155 ; 0000-0002-3687-6640 ; 0000-0001-7318-964X ; 0000-0003-3551-4549 ; Matematik Mühendisliği
    A novel image denoising model, namely Full Fractional Total Variation (TVFF), based on the Rudin-Osher-Fatemi (ROF) and the fractional total variation models is presented. The leading advantage of TVFF model is that it uses fractional derivatives with length scale parameters instead of ordinary derivatives with respect to both time and spatial variables in the diffusion equation. The Riesz–Caputo fractional derivative operator is used to disperse nonlocal influence throughout all directions, whereas the Caputo fractional derivative concept is employed for time fractional derivatives. Therefore, the influence of neighboring pixels is given greater weight compared to those situated farther away and this reflects the consideration behind denoising process better. Moreover, the numerical approach is constructed, and its stability and convergence properties are thoroughly examined. To show the superiority of our model, the denoised images are subjected to visual and numerical comparisons using metrics such as the Signal-to-Noise Ratio (SNR), the Structural Similarity Index Measure (SSIM) and the Edge-Retention Ratio (ERR). The performance of the TVFF method is evaluated under various types of noise, including Poisson, Speckle, and Salt & Pepper, and the results are compared with those obtained using Gauss and Median Filters. Furthermore, the proposed method is applied to both blind and synthetic images, thereby showcasing its versatility and applicability across diverse datasets. The outcomes showcase the substantial potential of our enhanced model as a versatile and efficient tool for image denoising.
  • Öge
    Machine learning based tomographic image reconstruction technique to detect hollows in wood
    (Springer, 2024) Yıldızcan, Ecem Nur ; Arı, Mehmet Erdi ; Tunga, Burcu ; Gelir, Ali ; Kurul, Fatih ; As, Nusret ; Dündar, Türker ; 0000-0001-6511-5587 ; 0000-0001-7659-6742 ; 0000-0001-7318-964X ; 0000-0001-6534-2253 ; Matematik Mühendisliği
    A new technique based on machine learning algorithms was introduced to detect internal wood defects. This technique relies on analyzing segmented propagation rays of stress waves and successfully generates the tomographic images of the defects by using the stress wave velocity. Utilizing a dual-stage methodology, the initial phase involves ray segmentation for the precise delineation of stress wave propagation, while the subsequent stage integrates advanced classification and clustering algorithms to facilitate the generation of tomographic images. This approach effectively tackles the inherent challenges associated with accurate segmentation and classification of stress wave velocity rays. The effectiveness of the proposed method was evaluated using both synthetic and experimental data. The results showed that the proposed method, when compared with some state-of-the-art methods, has a superior ability to accurately detect defective regions in the wood. The success of the proposed method is evaluated with four different evaluation metrics. It determined that over 90% success is achieved for all metrics. In comparison with related studies, it determined that the results are improved by 7–22% compared to the literature.
  • Öge
    Combination of polyethylenimine and vanillin-based benzoxazine as a straightforward self-healable system with excellent film-forming ability
    (American Chemical Society, 2024) Gülyüz, Sevinç ; Kışkan, Barış ; 0000-0002-3028-6455 ; 0000-0001-9476-2054 ; Kimya Bölümü
    This study introduces a straightforward and efficient route for synthesizing self-healable polybenzoxazine networks by utilizing dynamic imine bond exchanges under mild conditions. The process involves combining polyethylenimines with aldehyde-functional bisbenzoxazine, which was produced from vanillin, using a Sc(OTf)3 catalyst and subjecting them to moderate heating at 150 °C. Remarkably, the resulting polybenzoxazine films exhibit good self-healing capabilities at low temperatures and pressures, without requiring any additional additives to facilitate the healing process. The degree of recovery was assessed through tensile tests, while rheologic measurements were utilized to analyze stress relaxation and activation energy of dynamic bonding, providing insights into the self-healing process. Additionally, comprehensive spectral characterizations and investigations of thermal behaviors were conducted to gain a deeper understanding of the material’s properties and performance. Moreover, the polybenzoxazine networks demonstrated enhanced hydrolysis stability compared to conventional imine-based systems, benefiting from the specific Mannich linkages and inherent hydrophobic nature of polybenzoxazines.
  • Öge
    Comparison of dye adsorption of chitosan and polyethylenimine modified bentonite clays : optimization, isotherm, and kinetic studies
    (American Chemical Society, 2024) Kahya, Nilay ; Şen, Begüm ; Berber, Demet ; Öztekin, Nevin ; 0000-0002-7884-5113 ; 0000-0003-3676-5147 ; Kimya Mühendisliği
    The aim of this study was to compare the effect of modifying calcium bentonite (Bent-Ca) clay with two cationic polymers, chitosan (Chi) and polyethylenimine (PEI), on the removal of remazol black B (RB-B) dye from an aqueous solution. The samples were characterized by using scanning electron microscopy, X-ray diffraction, and Fourier-transform infrared spectroscopy. The fractional factorial design of 2(6–1) was applied to investigate the effects of pH, temperature, amount of adsorbent, initial dye concentration, contact time, and shaking rate on the adsorption process. To further optimize RB-B removal from an aqueous solution, a Box–Behnken design with three factors and a response surface methodology was used. The optimum conditions were a pH of 3.77, a temperature of 40.45 °C, and an initial RB-B concentration of 77.27 mg L–1 for Bent-Ca-Chi, whereas for Bent-Ca-PEI, the optimum conditions were a pH of 5.53, a temperature of 41.06 °C, and an initial dye concentration of 238.89 mg L–1. To understand the adsorption behavior, the Langmuir and Freundlich isotherms were fitted to the experimental data. It was found that the Langmuir isotherm model matched well with the dye adsorption by Bent-Ca-Chi and Bent-Ca-PEI. The kinetics study was performed using three kinetic models: pseudo-first-order, pseudo-second-order, and intraparticle diffusion models. Among these models, the RB-B dye kinetics were best represented by the pseudo-second-order model equation for the adsorbents.
  • Öge
    Supramolecular alternating polymers based on calix[4]pyrrole and pillar[5]arene molecular recognition
    (American Chemical Society, 2024) Memiş, Deniz ; Bektaş, Necla ; Aydoğan, Abdullah ; 0000-0002-0506-6020 ; 0000-0002-8944-3267 ; 0000-0001-6377-5143 ; Kimya Bölümü
    Supramolecular alternating polymers (SAPs) were constructed based on orthogonal interactions between an alkylnitrile-tethered calix[4]pyrrole and two different carboxylate-functionalized pillar[5]arene monomers possessing different chain lengths. Concurrent anion complexation and host–guest interactions were utilized by means of calix[4]pyrrole- and pillar[5]arene-based molecular recognitions. Characterization and multiresponsive behaviors of the resulting SAPs were characterized by means of a series of analyses, including various nuclear magnetic resonance techniques, viscosity measurements, and scanning electron microscopy. The resulting polymers were also applied to the fabrication of hierarchical materials with different dimensionalities. These materials include spherical aggregates with zero-dimensionality, fibers with one-dimensionality, two-dimensional microporous films, and finally three-dimensional materials. Current work represents the first example of SAPs based on calix[4]pyrrole and pillar[5]arene molecular recognition and is expected to be useful for designing and preparation of advanced, multicomponent synthetic self-assembled systems.
  • Öge
    High-performance thienothiophene and single wall carbon nanotube-based supercapacitor as a free-standing and flexible hybrid energy storage material
    (American Chemical Society, 2024) İşçi, Recep ; Dönmez, Koray Bahadır ; Karatepe, Nilgün ; Öztürk, Turan ; 0000-0003-3086-4478 ; 0000-0001-5315-3148 ; 0000-0002-7392-4103 ; 0000-0003-3777-5320 ; Kimya Bölümü
    Long cycle life and high energy/power density are imperative for energy storage systems. Similarly, flexible and free-standing electrodes are important for supercapacitor applications. Herein, we report, for the first time, use of thienothiophene (TT) and a single-walled carbon nanotube (SWCNT)-based free-standing and flexible hybrid material (TT-TPA-SWCNT) as a high-performance supercapacitor. The synthesized TT derivative, TT-TPA, was directly attached to SWCNT through noncovalent interactions to obtain the TT-based SWCNT hybrid, TT-TPA-SWCNT, as a flexible film. The hybrid film was clarified by surface analysis methods of scanning electron microscopy and atomic force microscopy. TT-TPA-SWCNT was used as a flexible and free-standing electrode in a two-electrode system for supercapacitor and energy storage applications. It displayed a high energy storage capacity of 83.2 F g–1 at 5 mV s–1 scan rate, an excellent cyclic stability with 110% retention of its initial specific capacitance after 7000 cycles and a long power density ranged from 100 to 3000 W·kg–1, demonstrating that TT-TPA-SWCNT is a promising hybrid nanomaterial for high-performance energy storage applications.