WoS İndeksli Yayınlar Koleksiyonu / WoS Indexed Publications Collection
Permanent URI for this collectionhttps://hdl.handle.net/11147/7150
Browse
31 results
Search Results
Article Polyaspartic Ester Polyurea-TiO2nanocomposite Coatings for UV Protection of Leading Edge of Wind Turbine Blades(Elsevier B.V., 2026) Olcer, Y.A.; Karabacak, B.D.; Demirkurt, M.; Yoldaş, İ.; Can y, Z.; Demir, M.Polyaspartic ester polyurea (PAEPU) supplies a promising matrix for high-durability coatings. However, its poor UV-A resistance make its usage limited. In this work, commercially available anatase TiO<inf>2</inf> particles (0.05–10 wt%) were dispersed in PAE matrix without any modification. PAEPU/TiO<inf>2</inf> composites were supplied by the reaction of PAE/TiO<inf>2</inf> matrix with an aliphatic isocyanate. UV–Visible spectra of spin coated PAEPU/TiO<inf>2</inf> composite thin films showed an exponential decrease in transmittance with increasing amount of TiO<inf>2.</inf> The optical response is dominated by UV blocking for TiO<inf>2</inf> amounts smaller than 0.3 wt%. For above 0.5 wt% TiO<inf>2</inf> amounts, transparency to translucency transition signifies the beginning of multiple scattering. The diameter of particles analyzed by AFM showed that particle diameter is 47 ± 11 nm taking into account of images of the PAEPU films containing 0.3 wt% of TiO<inf>2</inf> particles. Radial distribution function of the particle domains achieved from microscopy suggests that interparticle distance gets smaller than the wavelength of the incident light even at low the particle concentration. Accelerated weathering test were performed by applying 0.1, 0.5, 1.0, and 3.0 wt% TiO<inf>2</inf> containing PAEPU composite films on a white primer with Doctor Blade method. 0.1 wt% PAEPU/TiO<inf>2</inf> composites shows lower ΔE value compare to both neat and higher amounts of TiO<inf>2</inf> containing PAEPU composite films. The results suggest that without the complexity and cost of the surface modification, the low loading of commercial TiO<inf>2</inf> into PAE matrix may supply UV-stabilized PAEPU coatings relevant to the leading-edge protection of wind-turbine blades. © 2025 Elsevier B.V. All rights are reserved, including those for text and data mining, AI training, and similar technologies.Article A Simplified Molecular Imprinting Strategy Through Electrospinning of Polyacrylonitrile for Thin Film Microextraction of Selected Pesticides(Elsevier B.V., 2026) Şahin, A.; Akpinar, Y.; Yildirim, E.; Eroǧlu, A.E.; Boyaci, E.Molecularly imprinted polymers (MIPs) have been extensively used as selective extractive phases for sample preparation because of their analyte-selective binding sites. However, MIP preparation requires optimized monomer-template interactions and long polymerization reactions. In this study, a novel and simple method of MIP preparation was proposed based on electrospinning. Instead of preparing analyte-monomer complexes before polymerization, model analytes (trifluralin and carbaryl) were directly dissolved in a polyacrylonitrile (PAN) solution, then electrospun into nanofibrous mats. This allowed for a means of preparation of highly crystalline, template-imprinted nanostructures with minimal synthetic complexity. Following the characterization studies for the new material, the extraction properties of the imprinted and nonimprinted electrospun mats were investigated in thin film microextraction (TFME) studies by extracting trifluralin and carbaryl from water samples, followed by gas chromatography-mass spectrometry (GC–MS) analysis. The optimization results showed that samplers containing 10.0 mg of MIP sorbents made by electrospinning of a solution containing 5.0 mg of template in 1.0 mL of PAN solution resulted in approximately 4 and 7 times enhanced extraction recoveries for carbaryl and trifluralin compared to samplers made of non-imprinted bulk PAN. Moreover, the cross-reactivity testing performed with non-template analytes (malathion and diazinon) suggested a more specific extraction towards trifluralin compared to carbaryl. The proposed new technique was also validated using computational methodology, which supported the experimental finding about higher selectivity towards trifluralin. This may signify a probability for structural orientation of partially charged trifluralin under an electrical field in electrospun PAN creating favorable extraction sites. © 2025 Elsevier B.V.Article Citation - WoS: 3Citation - Scopus: 1Porous Polymer-Derived Ceramics for Environmental Applications: Sorption, Filtration, and Catalysis(Elsevier B.V., 2025) Icin, Oyku; Zeydanli, Damla; Biesuz, Mattia; Soraru, Gian Domenico; Vakifahmetoglu, CekdarPolymer-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: 8Citation - Scopus: 7Delignification of Corncob by Choline Chloride-Urea Deep Eutectic Solvent for Enzymatic Production of Xylooligosaccharides(Elsevier B.V., 2024) Yanak,S.; Buyukkileci,A.O.Deep eutectic solvent (DES) pretreatment was applied to corncob to obtain xylooligosaccharides (XOS) by enzymatic hydrolysis using xylanase. Based on the XOS titers in the hydrolysate, urea was the most effective among the hydrogen bond donors tested to couple choline chloride (ChCl). DES pretreatment at 130 °C for two hours with ChCl-Urea (molar ratio of 1:2) containing 40 % water, decreased lignin fraction from 12.8 % to 6.9 %, while 79 % of the xylan was retained in the pretreated corncob. The highest XOS production was obtained using 400 U/g xylanase at 60 °C, which yielded 12.0 g/L XOS with a low degree of polymerization (LDP-XOS). The total XOS yield based on the raw corncob was calculated as 14.4 %, 90 % of which was LDP-XOS. The cellulose-rich residual biomass could be hydrolyzed enzymatically to glucose with 65 % cellulose digestibility. The discarded biomass after hydrolyzes was 21.7 % of the raw material. The results showed that DES was a promising pretreatment for enhancing enzymatic XOS production. © 2024 Elsevier B.V.Article Citation - WoS: 4Citation - Scopus: 4Automating Modern Code Review Processes With Code Similarity Measurement(Elsevier B.V., 2024) Kartal,Y.; Akdeniz,E.K.; Özkan,K.Context: Modern code review is a critical component in software development processes, as it ensures security, detects errors early and improves code quality. However, manual reviews can be time-consuming and unreliable. Automated code review can address these issues. Although deep-learning methods have been used to recommend code review comments, they are expensive to train and employ. Instead, information retrieval (IR)-based methods for automatic code review are showing promising results in efficiency, effectiveness, and flexibility. Objective: Our main objective is to determine the optimal combination of the vectorization method and similarity to measure what gives the best results in an automatic code review, thereby improving the performance of IR-based methods. Method: Specifically, we investigate different vectorization methods (Word2Vec, Doc2Vec, Code2Vec, and Transformer) that differ from previous research (TF-IDF and Bag-of-Words), and similarity measures (Cosine, Euclidean, and Manhattan) to capture the semantic similarities between code texts. We evaluate the performance of these methods using standard metrics, such as Blue, Meteor, and Rouge-L, and include the run-time of the models in our results. Results: Our results demonstrate that the Transformer model outperforms the state-of-the-art method in all standard metrics and similarity measurements, achieving a 19.1% improvement in providing exact matches and a 6.2% improvement in recommending reviews closer to human reviews. Conclusion: Our findings suggest that the Transformer model is a highly effective and efficient approach for recommending code review comments that closely resemble those written by humans, providing valuable insight for developing more efficient and effective automated code review systems. © 2024 Elsevier B.V.Article Citation - WoS: 5Citation - Scopus: 6Fabrication of Gelatin-Polyester Based Biocomposite Scaffold Via One-Step Functionalization of Melt Electrowritten Polymer Blends in Aqueous Phase(Elsevier B.V., 2024) Köksal,B.; Kartal,R.B.; Günay,U.S.; Durmaz,H.; Yildiz,A.A.; Yildiz,Ü.H.The rapid manufacturing of biocomposite scaffold made of saturated-Poly(ε-caprolactone) (PCL) and unsaturated Polyester (PE) blends with gelatin and modified gelatin (NCO-Gel) is demonstrated. Polyester blend-based scaffold are fabricated with and without applying potential in the melt electrowriting system. Notably, the applied potential induces phase separation between PCL and PE and drives the formation of PE rich spots at the interface of electrowritten fibers. The objective of the current study is to control the phase separation between saturated and unsaturated polyesters occurring in the melt electro-writing process and utilization of this phenomenon to improve efficiency of biofunctionalization at the interface of scaffold via Aza-Michael addition reaction. Electron-deficient triple bonds of PE spots on the fibers exhibit good potential for the biofunctionalization via the aza-Michael addition reaction. PE spots are found to be pronounced in which blend compositions are PCL-PE as 90:10 and 75:25 %. The biofunctionalization of scaffold is monitored through C[sbnd]N bond formation appeared at 400 eV via X-ray photoelectron spectroscopy (XPS) and XPS chemical mapping. The described biofunctionalization methodology suggest avoiding use of multi-step chemical modification on additive manufacturing products and thereby rapid prototyping of functional polymer blend based scaffolds with enhanced biocompatibility and preserved mechanical properties. Additionally one-step additive manufacturing method eliminates side effects of toxic solvents and long modification steps during scaffold fabrication. © 2024 Elsevier B.V.Article Citation - WoS: 1Citation - Scopus: 1The Harmonic Oscillator Potential Perturbed by a Combination of Linear and Non-Linear Dirac Delta Interactions With Application To Bose–einstein Condensation(Elsevier B.V., 2024) Akyüz,C.; Erman,F.; Uncu,H.In this paper, we study the bound state analysis of a one dimensional nonlinear version of the Schrödinger equation for the harmonic oscillator potential perturbed by a δ potential, where the nonlinear term is taken to be proportional to δ(x)|ψ(x)|2ψ(x). The bound state wave functions are explicitly found and the bound state energy of the system is algebraically determined by the solution of an implicit equation. Then, we apply this model to the Bose–Einstein condensation of a Bose gas in a harmonic trap with a dimple potential. We propose that the many-body interactions of the Bose gas can be effectively described by the nonlinear term in the Schrödinger equation. Then, we investigate the critical temperature, the condensate fraction, and the density profile of this system numerically. © 2024 Elsevier B.V.Article Citation - WoS: 7Citation - Scopus: 7Contributory Roles of Concentration and Ph in Caco3 Growth Inhibition for Submicron Particles Synthesis With Additive Ca2+(Elsevier B.V., 2024) Majekodunmi,O.T.; Kilic,S.; Ozdemir,E.Excessive growth of CaCO3 precipitates is inhibited by additive Ca2+. Here, we report the influence of concentration and solution pH on the extent of growth inhibition. Equal volumes of equimolar CaCl2 and Na2CO3 solutions were mixed and continuously dispersed in Ca(OH)2 solution, where Ca2+ irreversibly adsorb on the precipitates. Compared to conditions where additive Ca2+ are absent, this method can produce more than 90% decrease in particle size. We observe the degree of growth inhibition increases as the concentration of additive Ca2+, relative to the volume of precipitates, increases. An unusual role of pH is also revealed: growth inhibition that leads to the synthesis of monodisperse submicron CaCO3 particles is only observed in high alkaline pH conditions. Additive Ca2+ adsorb on CaCO3 precipitates in pH conditions above the isoelectric point (pH ≈ 9), but their ability to limit CaCO3 growth diminishes when pH < 12. © 2024 Elsevier B.V.Article Citation - WoS: 4Citation - Scopus: 3Ligand Engineering for Improving the Stability and Optical Properties of Cspbi3 Perovskite Nanocrystals(Elsevier B.V., 2024) Yuce Cakir,H.; Yalcinkaya,Y.; Demir,M.M.Inorganic lead halide perovskite nanocrystals (NCs) have recently become one of the research topics for optoelectronic applications due to their excellent photophysical properties. Despite their notable thermal stability over organic-inorganic halide perovskites, CsPbI3 NCs suffer from the phase instability of α-CsPbI3 phase at room temperature and under ambient conditions. Here, the effects of 4-Hydroxybenzoic acid (4-HBA) as an additive to standard oleic acid – oleylamine pair on the stability and optical properties of CsPbI3 perovskite NCs are discussed. 4-HBA addition into perovskite NC systems causes a compressive strain on perovskite lattice, which leads to the formation of a mixed phase α- and γ-CsPbI3 phases while pristine perovskite has α-CsPbI3 phase. Time-dependent stability of the perovskite NCs was tested under an ethanol (EtOH) medium. After EtOH exposure of the perovskite NCs, CsPbI3 NCs transformed to non-perovskite phase in 1 h while 4-HBA added CsPbI3 NCs still have perovskite phase after 48 h. In addition to the improved optical properties of the perovskite NCs, 4-HBA addition remarkably improves CsPbI3 perovskite stability. © 2024 Elsevier B.V.Article Citation - WoS: 8Citation - Scopus: 8Fast-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