WoS İndeksli Yayınlar Koleksiyonu / WoS Indexed Publications Collection
Permanent URI for this collectionhttps://hdl.handle.net/11147/7150
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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: 2Citation - Scopus: 2A Comprehensive Study on the Effectiveness of the Stress and Damage Model Parameters in Predicting the Compression Fracture Behavior of Selective Laser Melted AlSi10Mg BCC Lattices(Elsevier B.V., 2025) Guden, Mustafa; Erten, Hacer Irem; Gorguluarslan, Recep M.; Gulletutan, Umut Can; Dagkolu, Akin; Gokdag, Istemihan; Namazov, SubhanThe Johnson and Cook (JC) stress and damage model parameters determined from the machined bulk cylindrical specimens and as-built struts through tension and compression tests were used to model quasi-static compression behavior of selective laser melt-fabricated AlSi10Mg alloy lattices. The lattices had the same cell size (10 mm) and strut diameter (1 mm), but different number of cells (2 x 2 x 2, 10 x 10 x 2 and 5 x 5 x 5) and geometries (sandwich and cubic). Four different sets of JC damage model parameters (brittle and ductile notch-insensitive and compression and tension notch-sensitive) were further implemented in the lattice compression numerical models. The brittle damage model parameters and smaller mesh sizes resulted in cracking the face-sheet corner strut nodes before the occurrence of a bending-dominated initial peak stress. The notch-sensitive damage model parameters exhibited no bent-strut fracture in the middle layers of the lattices and increased the crack initiation strains as compared with the notch-insensitive damage model parameters. Despite significant variations in the initial peak stresses of the tested 2 x 2 x 2 and 10 x 10 x 2 lattices, the implication of the strut micro-tension stress model together with the compression notch-sensitive damage model parameters using 0.25 mm mesh size conservatively approximated the experimental deformation stresses while the machined bulk specimen tensionstress model over predicted the experimental stresses. On the other side, the strut stress model with 0.15 mm mesh size accurately predicted the experimental diagonal shear/fracture mode of struts with a slightly higher numerical initial peak stress. The compression tests on the strut specimens extracted from the as-built lattices yielded similar stress model parameters with the micro-tension tests. The differences between the initial peak stresses of the investigated sandwich and cubic lattices were further explained by the differences in the lattice boundary conditions.Article Citation - WoS: 4Citation - Scopus: 4Novel Electrospun-Based Extractive Probes for Rapid Determination of Clinically Important Compounds in Human Plasma(Elsevier B.V., 2024) Temel,E.R.; Eroğlu,A.E.; Salih,B.; Boyaci,E.Background: Coated blade spray (CBS) represents an innovative approach that utilizes solid-phase microextraction principles for sampling and sample preparation. When combined with ambient mass spectrometry (MS), it can also serve as an electrospray ionization source. Therefore, it became a promising tool in analytical applications as it can significantly reduce the analysis time. However, the current CBS coatings are based on the immobilization of extractive particles in bulk polymeric glue, which constrains the diffusion of the analytes to reach the extractive phase; therefore, the full reward of the system cannot be taken at pre-equilibrium. This has sparked the notion of developing new CBS probes that exhibit enhanced kinetics. Results: With this aim, to generate a new extractive phase with improved extraction kinetics, poly(divinylbenzene) (PDVB) nanoparticles were synthesized by mini-emulsion polymerization and then immobilized into sub-micrometer (in diameter) sized polyacrylonitrile fibers which were obtained by electrospinning method. Following the optimization and characterization studies, the electrospun-coated blades were used to determine cholesterol, testosterone, and progesterone in plasma spots using the CBS-MS approach. For testosterone and progesterone, 10 ng mL−1 limits of quantification could be obtained, which was 200 ng mL−1 for cholesterol in spot-sized samples without including any pre-treatment steps to samples prior to extraction. Significance: The comparison of the initial kinetics for dip-coated and electrospun-coated CBS probes proved that the electrospinning process could enhance the extraction kinetics; therefore, it can be used for more sensitive analyses. The total analysis time with this method, from sample preparation to instrumental analysis, takes only 7 min, which suggests that the new probes are promising for fast diagnostic applications. © 2024 Elsevier B.V.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: 13Citation - Scopus: 12Dunaliella Salina Microalgae Aqueous Extract-Based Magnetic Nanoparticles (fe3o4-Nps): Green Synthesis, Characterization and in Vitro Anticancer Investigations(Elsevier B.V., 2024) Jafari,N.; Hamishehkar,H.; Mohammadpourfard,M.In the current study, a facile, rapid, and eco-friendly method was provided for green synthesizing of magnetic Fe3O4-NPs with enhanced stability and biocompatibility using different weight concentrations (1 %, 3 %, and 5 %) of aqueous extract of Dunaliella salina (D. salina) microalgae. The properties of the green-synthesized magnetic nanoparticles (GMNPs-ex1%, GMNPs-ex3%, and GMNPs-ex5%) were compared with chemically-synthesized ones (CMNPs) via XRD, TEM, FESEM, VSM, DLS, ZP, FTIR, hemolysis, cell viability, DAPI staining, and apoptosis analyses. TEM imaging revealed mean sizes of 11.21 ± 2.63 nm and 14.08 ± 3.24 nm for GMNPs-ex5% and CMNPs, respectively, with better dispersity for GMNPs-ex5%, as confirmed with their polydispersity index (PDI = 0.24 for GMNPs-ex5% and 0.58 for CMNPs). These sizes were consistent with the crystallite size of pure magnetite phase nanoparticles obtained from XRD. FESEM images confirmed spherical shape for the majority of nanoparticles. FTIR spectra confirmed the involvement of functional groups from the extract in GMNPs, contributing to their stability (ZP of GMNPs-ex5% = −34 mV). The saturation magnetization decreased with increasing the extract ratio (from 62.41 to 8.94 emu/g), attributed to the non-magnetic nature of the extract coating. GMNPs-ex5% exhibited a negligible hemolysis rate (< 2 %) compared to CMNPs. Furthermore, IC50 values of GMNPs and extract against HFF-2 and A549 cells were higher than those of CMNPs, indicating the biocompatibility of green-synthesized nanoparticles. In the DAPI staining method, GMNPs-ex5%, similar to the extract, caused less DNA damage to HFF-2 cells. Additionally, the apoptosis assay using annexin V/PI staining kit indicated that green-synthesized nanoparticles induced lower apoptosis in normal cells. Overall, this study highlights the potential of green-synthesized Fe3O4-NPs for various biomedical applications, showcasing their enhanced properties and biocompatibility compared to conventionally synthesized counterparts. © 2024 Elsevier B.V.Article Effects of Edge Addition or Removal on the Nullity of a Graph(Elsevier B.V., 2024) Batal,A.Lights Out is a game which can be played on any graph G. Initially we have a configuration which assigns one of the two states on or off to each vertex. The aim of the game is to turn all vertices to off state for an initial configuration by activating some vertices where each activation switches the state of the vertex and all of its neighbors. If the aim of the game can be accomplished for all initial configurations then G is called always solvable. We call the dimension of the kernel of the closed neighborhood matrix of the graph over the field Z2, nullity of G. It turns out that G is always solvable if and only if its nullity is zero. Moreover, the number of solutions of a given configuration is also determined by the nullity. We investigate the problem of how nullity changes when an edge is added to or removed from a graph. As a result we show that for every graph with positive nullity there exists an edge whose removal decreases the nullity. Conversely, we show that for every always solvable graph which is not an even graph with odd order, there exists an edge whose addition increases the nullity. We also show that if an always solvable graph is not even, then there is an edge whose removal increases the nullity. © 2024Article Citation - WoS: 10Citation - Scopus: 11Arabinoxylan-Based Psyllium Seed Hydrocolloid: Single-Step Aqueous Extraction and Use in Tissue Engineering(Elsevier B.V., 2024) Yildirim-Semerci,Ö.; Bilginer-Kartal,R.; Arslan-Yildiz,A.Biomacromolecules derived from natural sources offer superior biocompatibility, biodegradability, and water-holding capacity, which make them promising scaffolds for tissue engineering. Psyllium seed has gained attention in biomedical applications recently due to its gel-forming ability, which is provided by its polysaccharide-rich content consisting mostly of arabinoxylan. This study focuses on the extraction and gelation of Psyllium seed hydrocolloid (PSH) in a single-step water-based protocol, and scaffold fabrication using freeze-drying method. After characterization of the scaffold, including morphological, mechanical, swelling, and protein adsorption analyses, 3D cell culture studies were done using NIH-3 T3 fibroblast cells on PSH scaffold, and cell viability was assessed using Live/Dead and Alamar Blue assays. Starting from day 1, high cell viability was obtained, and it reached 90 % at the end of 15-day culture period. Cellular morphology on PSH scaffold was monitored via SEM analysis; cellular aggregates then spheroid formation were observed throughout the study. Collagen Type-I and F-actin expressions were followed by immunostaining revealing a 9- and 10-fold increase during long-term culture. Overall, a single-step and non-toxic protocol was developed for extraction and gelation of PSH. Obtained results unveiled that PSH scaffold provided a favorable 3D microenvironment for cells, holding promise for further tissue engineering applications. © 2024 Elsevier B.V.Article Citation - WoS: 3Citation - Scopus: 3Macroporous 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