WoS İndeksli Yayınlar Koleksiyonu / WoS Indexed Publications Collection

Permanent URI for this collectionhttps://hdl.handle.net/11147/7150

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Now showing 1 - 10 of 29
  • Article
    Citation - WoS: 3
    Citation - Scopus: 1
    Porous Polymer-Derived Ceramics for Environmental Applications: Sorption, Filtration, and Catalysis
    (Elsevier B.V., 2025) Icin, Oyku; Zeydanli, Damla; Biesuz, Mattia; Soraru, Gian Domenico; Vakifahmetoglu, Cekdar
    Polymer-derived ceramics (PDCs), obtained from preceramic polymers, have emerged as promising materials for environmental applications due to their high thermal and chemical stability, tunable nano-microstrucure and porosity, and versatile surface functionalities. This review focuses on the recent advances in porous PDCs and their use in key environmental fields such as sorption, filtration, and catalysis. A comparative analysis of precursor chemistry, synthesis strategies, and resulting structural properties is presented, emphasizing how these factors influence performance in environmental remediation tasks. By consolidating findings across specific application areas, the work aims to clarify the functional potential of PDCs and identify current research gaps and opportunities for future development in environmental material science.
  • Article
    Citation - WoS: 3
    Citation - Scopus: 3
    Hybrid Silica Aerogels From Bridged Silicon Alkoxides: Ultralow Thermal Conductivity for Low-Temperature Applications
    (Springer, 2025) Abebe, A. M.; Biesuz, M.; Vakifahmetoglu, C.; Cassetta, M.; Soraru, G. D.
    Hybrid silica aerogels are promising materials for thermal insulation applications. Highly porous aerogels were synthesized from bridged bis(triethoxysilyl)methane BTEM and triethoxysilane TREOS silicon alkoxides via the sol-gel process. The carbon content in the hybrid aerogels decreased with increasing amounts of TREOS. Crack-free monolith aerogels were synthesized through supercritical drying, which is crucial for thermal and optical investigations. The aerogels are characterized by high BET surface areas ranging from 700 to 1400 m(2)/g, pore volumes between 2.0 and 10.5 cm(3)/g, and a maximum porosity of 95%. The thermal conductivity of the aerogels at room temperature was measured via a hot disk apparatus. The materials exhibited ultralow thermal conductivity, reaching a minimum value of 15 mW/mK. This value ranks among the lowest reported values for silica-based aerogels in the literature. Optical transmittance measurements indicated high transparency, exceeding 80% in the visible region. Therefore, these exceptional properties of low density, high optical transparency, and low thermal conductivity make these materials promising candidates for transparent insulation applications.
  • Article
    Nitrate Sensing With Molecular Cage Ionophores: a Potentiometric Approach
    (Royal Soc Chemistry, 2025) Onder, Ahmet; Begar, Ferit; Kibris, Erman; Buyukcakir, Onur; Yildiz, Umit Hakan
    Nitrate ions are widespread environmental pollutants in water and soil, posing critical risks to both human health and ecosystems. This study introduces a molecular cage as a novel ionophore for potentiometric nitrate-selective ion-selective electrodes (ISEs) designed for enhanced specificity and sensitivity. Among six synthetic candidates, the electrode incorporating a 1,3,5-tri(p-hydroxyphenyl)benzene-based chlorotriazine pillared cage molecule (CAGE-1) exhibited superior performance, characterized by a linear response in the nitrate concentration range of 1.0 x 10-5 to 1.0 x 10-1 M, with a high coefficient of determination (R2 = 0.9971) and a slope of -53.1 +/- 1.4 mV dec-1. The electrode also achieved a limit of detection of 7.5 x 10-6 M. These findings highlight the potential of molecular cages as ionophores for nitrate sensing in environmental applications.
  • Article
    Citation - WoS: 3
    Citation - Scopus: 3
    Macroporous Polymer-Derived Ceramics Produced by Standard and Additive Manufacturing Methods: How the Shaping Technique Can Affect Their High Temperature Thermal Behavior
    (Elsevier B.V., 2024) Zambotti,A.; Kulkarni,A.; Semerci,T.; Vakifahmetoglu,C.; Pelanconi,M.; Bottacin,S.; Sorarù,G.D.
    This work proposes the processing of porous ceramic lattices via three polymer-derived ceramic routes, namely powder bed fusion and infiltration, fused filament fabrication and replica, and a direct replica of a foamed polymer. A common feature in the processing of these lattices is the use of the same polysilazane as the preceramic source for the Si-C-N-O network that builds up during ceramization. We adopted rotated cube, honeycomb and randomized cellular geometries as a matter of comparison for thermal exchange when an air flow is forced through the structures up to 1050 °C. The three procedural pathways are discussed in their limitations regarding geometry, polymer-to-ceramic conversion, high-temperature heat exchange performance and durability. In this regard, while rotated cube geometry results in the best thermal exchange and highest pressure drop, we show a correlation between chemical composition and high temperature oxidation of the Si-C-N-O network, possibly attributed to the selection of the processing routes. © 2024 The Authors
  • Article
    Citation - WoS: 1
    Citation - Scopus: 2
    Identifying Promoter and Enhancer Sequences by Graph Convolutional Networks
    (Elsevier Ltd, 2024) Tenekeci,S.; Tekir,S.
    Identification of promoters, enhancers, and their interactions helps understand genetic regulation. This study proposes a graph-based semi-supervised learning model (GCN4EPI) for the enhancer-promoter classification problem. We adopt a graph convolutional network (GCN) architecture to integrate interaction information with sequence features. Nodes of the constructed graph hold word embeddings of DNA sequences while edges hold the Enhancer-Promoter Interaction (EPI) information. By means of semi-supervised learning, much less data (16%) and time are needed in model training. Comparisons on a benchmark dataset of six human cell lines show that the proposed approach outperforms the state-of-the-art methods by a large margin (10% higher F1 score) and has the fastest training time (up to 3 times). Moreover, GCN4EPI's performance on cross-cell line data is also better than the baselines (3% higher F1 score). Our qualitative analyses with graph explainability models prove that GCN4EPI learns from both text and graph structure. The results suggest that integrating interaction information with sequence features improves predictive performance and compensates for the number of training instances. © 2024
  • Article
    Citation - WoS: 8
    Citation - Scopus: 8
    Fast-Firing of Potassium Sodium Niobate (knn)
    (Elsevier B.V., 2024) Karacasulu,L.; Karakaya,M.; Adem,U.; Sglavo,V.M.; Biesuz,M.; Vakifahmetoglu,C.
    Potassium sodium niobate (KNN) is one of the most promising Pb-free piezo-ceramics. In the present work, KNN was produced by fast-firing with different cooling strategies, i.e., fast and slow cooling. Dielectric, ferroelectric, and piezoelectric properties of fast-fired pellets were determined and compared with those of conventional-sintered products. Although the samples produced by fast-firing had higher density than those obtained by conventional sintering, fast-cooled samples following fast firing show relatively low electrical properties. When fast-firing was combined with slow cooling, the electrical properties, especially piezoelectric d33 values, were improved. The material subjected to fast-firing at 1120 °C using slow cooling gave the highest relative density (about 95 %) with fine grains microstructure and a d33 of 112 pC/N whereas that produced by conventional sintering resulted in d33 of 80 pC/N with a relative density of 88 % for the same dwell time (30 min). © 2024 The Authors
  • Article
    Citation - WoS: 6
    Citation - Scopus: 7
    Acid-Derived Bacterial Cellulose Nanocrystals as Organic Filler for the Generation of High-Oxygen Barrier Bio-Nanocomposite Coatings
    (Royal Soc Chemistry, 2023) Carullo, Daniele; Rovera, Cesare; Bellesia, Tommaso; Büyüktaş, Duygu; Ghaani, Masoud; Santo, Nadia; Farris, Stefano
    Macro-sized bacterial cellulose (BC) derived from Komagataeibacter sucrofermentans was down-sized into nanocrystals (BCNCs) through hydrochloric acid (H-BCNCs) and sulfuric acid (S-BCNCs) hydrolysis. Initially, aqueous dispersions of BCNCs were analyzed for stability, size/morphology, and optical/mechanical properties. Subsequently, BCNCs were incorporated into a main biopolymer phase (i.e., pullulan) to create bio-nanocomposite coatings with high-oxygen barrier performance. Upon treatment with sulfuric acid, nano-sized particles (approximate to 240 nm) were observed, contrasting with significantly larger sizes (approximate to 1.8 mu m) seen for particles obtained using hydrochloric acid. Microscopy analyses revealed a needle-like morphology of the nanocrystals, which appeared organized in stacks for H-BCNCs or as individual units for S-BCNCs. Pullulan/BCNCs coatings applied to polyethylene-terephthalate (PET) films improved the gas barrier performance of the original substrate, by dramatically reducing the oxygen transmission rate (OTR) values from approximate to 120 cm3 m-2 24 h-1 to approximate to 2 cm3 m-2 24 h-1 while preserving its original optical and mechanical properties. Our developed bionanocomposite-coated PET films hold potential as an alternative material for various food packaging applications. This study investigates the effect of the hydrolysis process on bacterial cellulose (BC) to obtain bacterial cellulose nanocrystals (BCNCs) used to create high oxygen barrier nanocomposite coatings for food packaging applications.
  • Article
    Arithmetic Progressions in Certain Subsets of Finite Fields
    (Elsevier, 2023) Eyidoğan, Sadık; Göral, Haydar; Kutlu, Mustafa Kutay
    In this note, we focus on how many arithmetic progressions we have in certain subsets of finite fields. For this purpose, we consider the sets Sp = {t2 : t & ISIN; Fp} and Cp = {t3 : t & ISIN; Fp}, and we use the results on Gauss and Kummer sums. We prove that for any integer k & GE; 3 and for an odd prime number p, the number of k-term arithmetic progressions in Sp is given by p2 2k + R, where and ck is a computable constant depending only on k. The proof also uses finite Fourier analysis and certain types of Weil estimates. Also, we obtain some formulas that give the exact number of arithmetic progressions of length  in the set Sp when  & ISIN; {3,4, 5} and p is an odd prime number. For  = 4, 5, our formulas are based on the number of points on
  • Article
    Citation - WoS: 2
    Citation - Scopus: 2
    Gas Phase Fragmentation Behavior of Proline in Macrocyclic B7 Ions
    (American Chemical Society, 2023) Taşoğlu, Çağdaş; Arslanoğlu, Alper; Yalçın, Talat
    Thefragmentation characteristics of b (7) ionsproduced from proline-containing heptapeptides have been studiedin detail. The study has utilized the following C-terminally amidatedmodel peptides: PA(6), APA(5), A(2)PA(4), A(3)PA(3), A(4)PA(2), A(5)PA, A(6)P, PYAGFLV, PAGFLVY, PGFLVYA, PFLVYAG,PLVYAGF, PVYAGFL, YPAGFLV, YAPGFLV, YAGPFLV, YAGFPLV, YAGFLPV, YAGFLVP,PYAFLVG, PVLFYAG, A(2)PXA(3), and A(2)XPA(3) (where X = C, D, F, G, L, V, and Y, respectively). The resultshave shown that b (7) ions undergo head-to-tailcyclization and form a macrocyclic structure. Under the collision-induceddissociation (CID) condition, it generates nondirect sequence ionsregardless of the position of the proline and the neighboring aminoacid residues. This study highlights the unusual and unique fragmentationbehavior of proline-containing heptapeptides. Following the head-to-tailcyclization, the ring opens up and places the proline residue in theN-terminal position while forming a regular oxazolone form of b (2) ions for all peptide series. Then, the fragmentationreaction pathway is followed by the elimination of proline with itsC-terminal neighbor residue as an oxazolone (e.g., PXoxa) for all proline-containing peptide series.
  • Article
    Citation - WoS: 3
    Citation - Scopus: 3
    Selfless Subjectivities That (re)build the Nation: Remaking the Modern Turkish Woman in the Early Republican Period in Turkiye
    (SAGE Publications, 2023) Yakalı, Dikmen; Ataman, Bora
    This study explores the newly constructed female identities of the Early Republican Era in Turkiye (1923-1945). Through a thematic analysis of three contemporary women's magazines (Aile Dostu, Ev-Is, and Asrin Kadini) it aims to examine how conceptualizations of marriage and family were refashioned in the magazines to fit in the images within the newly constructed domestic ideologies of the state. We argue that the selfless subjectivities offered by the magazines point to dialogically constructed narrative identities which are not stable but fluid. The women's magazines of the Era aimed to reconstruct new identities by representing the Republic's ideas and official ideology to its people. Thus, they became one of the tools of social engineering in the way of transforming the nation into a modern, Westernized one. Analysing these magazines help us identify the repertoire of subjectivities and narrative identities from which women drew while making sense of their selves during an era of transformation.