Materials Science and Engineering / Malzeme Bilimi ve Mühendisliği
Permanent URI for this collectionhttps://hdl.handle.net/11147/4719
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Article Citation - WoS: 101Citation - Scopus: 105Defect-Engineering Agsbte2 With High Thermoelectric Performance(Wiley, 2023) Zhang, Yu; Li, Zhi; Singh, Saurabh; Nozariasbmarz, Amin; Li, Wenjie; Genç, Aziz; Xia, YiThermoelectric (TE) generators enable the direct and reversible conversion between heat and electricity, providing applications in both refrigeration and power generation. In the last decade, several TE materials with relatively high figures of merit (zT) have been reported in the low- and high-temperature regimes. However, there is an urgent demand for high-performance TE materials working in the mid-temperature range (400–700 K). Herein, p-type AgSbTe2 materials stabilized with S and Se co-doping are demonstrated to exhibit an outstanding maximum figure of merit (zTmax) of 2.3 at 673 K and an average figure of merit (zTave) of 1.59 over the wide temperature range of 300–673 K. This exceptional performance arises from an enhanced carrier density resulting from a higher concentration of silver vacancies, a vastly improved Seebeck coefficient enabled by the flattening of the valence band maximum and the inhibited formation of n-type Ag2Te, and ahighly improved stability beyond 673 K. The optimized material is used to fabricate a single-leg device with efficiencies up to 13.3% and a unicouple TE device reaching energy conversion efficiencies up to 12.3% at a temperature difference of 370 K. These results highlight an effective strategy to engineer high-performance TE material in the mid-temperature range.Article Citation - WoS: 6Citation - Scopus: 6Polar Solvent-Free Room Temperature Synthesis of Cspbx3 (x = Br, Cl) Perovskite Nanocubes(Royal Society of Chemistry, 2023) Güvenç, Çetin Meriç; Kocabaş, Aşkın; Balcı, SinanConventionally, colloidal lead halide perovskite nanocubes have been synthesized by the hot-injection or ligand-assisted reprecipitation (LARP) methods. We herein demonstrate a polar solvent-free room temperature method for the synthesis of CsPbX3 (X = Br, Cl) nanocubes. In addition to the commonly used ligand pair of oleylamine and oleic acid, guanidinium (GA) has been used to passivate the surface of the nanocrystals. Our study demonstrates that GA inhibits the formation of low dimensional structures such as nanowires and nanoplatelets and further supports the formation of perovskite nanocubes. In fact, GA diminishes the restricted monomer-addition effect of long-chain oleylammonium (OLAM) ions to the nanocrystal. We show that above a critical GA/OLAM molar ratio, the synthesis yields homogeneous CsPbX3 (X = Br, Cl) nanocubes. Importantly, we observe the nucleation and growth kinetics of the GA-assisted CsPbBr3 nanocube formation by using in situ absorption and photoluminescence (PL) measurements. Small nanocrystals with an excitonic absorption peak at around 435 nm and photoluminescence (PL) maxima at 447 nm were nucleated and continuously shifted to longer wavelengths during the growth period. Crucially, our method allows the synthesis of CsPbCl3 nanocubes at room temperature without using polar organic solvents. The synthesized CsPbBr3, CsPb(Cl0.5Br0.5)3, and CsPbCl3 nanocubes have PL peaks at 508 nm, 443 nm, and 405 nm, photoluminescence quantum yields (PLQY) of 85%, 58% and 5%, and lifetimes of 18.98 ns, 18.97 ns, and 14.74 ns, respectively.Article Citation - WoS: 2Citation - Scopus: 2Size Driven Barrier To Chirality Reversal in Electric Control of Magnetic Vortices in Ferromagnetic Nanodiscs(Royal Society of Chemistry, 2022) Aldulaimi, W. A. S.; Okatan, Mahmut Barış; Şendur, Kürşat; Onbaşlı, Mehmet Cengiz; Mısırlıoğlu, İbrahim BurçNew high density storage media and spintronic devices come about with a progressing demand for the miniaturization of ferromagnetic structures. Vortex ordering of magnetic dipoles in such structures has been repeatedly observed as a stable state, offering the possibility of chirality in these states as a means to store information at high density. Electric pulses and magnetoelectric coupling are attractive options to control the chirality of such states in a deterministic manner. Here, we demonstrate the chirality reversal of vortex states in ferromagnetic nanodiscs via pulsed electric fields using a micromagnetic approach and focus on the analysis of the energetics of the reversal process. A strong thickness dependence of the chirality reversal in the nanodiscs is found that emanates from the anisotropy of the demagnetizing fields. Our results indicate that chiral switching of the magnetic moments in thin discs can give rise to a transient vortex-antivortex lattice not observed in thicker discs. This difference in the chirality reversal mechanism emanates from profoundly different energy barriers to overcome in thin and thicker discs. We also report the polarity-chirality correlation of a vortex that appears to depend on the aspect ratio of the nanodiscs.Article Citation - WoS: 10Citation - Scopus: 9Recyclability of Cspbbr3 Quantum Dot Glass Nanocomposites for Their Long-Standing Use in White Leds(2022) Vahedigharehchopogh, Naji; Erol, Erdinç; Kıbrıslı, Orhan; Genç, Aziz; Çelikbilek Ersundu, Miray; Ersundu, Ali ErçinThe embedding of CsPbBr3 perovskite quantum dots (PQDs) in an inorganic glass matrix not only protects them against chemical, thermal, and photodegradation but also provides an effective strategy to isolate toxic elements such as Pb from the environment for a long period of time. Herein, the recyclability of glass is another important feature that contributes to environmental sustainability. Hence, effective and efficient recycling technologies are needed for the widespread use of PQD glass nanocomposites (GNCs) in many commercial applications. However, studies on the recyclability of CsPbBr3 PQD GNCs have not been conducted so far. Therefore, in this work, we investigate the structural, thermal, optical, and photoluminescence properties of recycled CsPbBr3 PQD GNCs to assess their suitability as long-standing and reusable luminescent materials. For this purpose, the recyclability of GNCs is checked by three repeated melt-quenching and subsequent heat-treatment processes. Although the color emission properties of GNCs under the same heat-treatment conditions show a slight variation after each recycling step, PQD GNCs almost retain their PLQY even after the last recycling step. Ultimately, a prototype white light-emitting diode is constructed by coupling recycled PQD GNCs and a commercial red phosphor on top of a blue LED chip showing high-performance with CIE color coordinates of x = 0.3228, y = 0.3470 and a CCT value of 5920 K. The findings of this work reveal that the recyclability of PQD GNCs holds great promise for a more sustainable technology.Article Citation - WoS: 13Citation - Scopus: 14Synthesis of Albumin Nanoparticles in a Water-Miscible Ionic Liquid System, and Their Applications for Chlorambucil Delivery To Cancer Cells(Elsevier, 2022) Akdoğan, Yaşar; Sözer, Sümeyra Çiğdem; Akyol, Cansu; Başol, Merve; Karakoyun, Çiğdem; Çakan Akdoğan, GülçinSerum albumin has been a preferred protein to generate biodegradable and non-toxic nanoparticles (NPs) for drug delivery applications. Different methods applied for the preparation of serum albumin NPs mostly used organic solvents. Here, we prepared serum albumin NPs in an ionic liquid (IL) system. ILs are considered to be green and designer solvents with unique properties that can replace organic solvents in the synthesis of albumin NPs. Bovine serum albumin (BSA) proteins dissolved in water were transformed into BSA NPs in a water/ Triton™X (TX-100), 1-butanol/1-butyl-3-methylimidazolium trifluoromethanesulfonate (BmimCF3SO3) microemulsion-like system by using a high-speed homogenizer and crosslinker glutaraldehyde. The obtained BSA NPs have been used in drug loading and release studies with a hydrophobic anticancer drug chlorambucil (Chl). Drug loading increased as increasing the ratio of Chl incubated with BSA NPs. Monitoring the drug release by UV–Vis spectroscopy revealed a burst release at first 4 h, but two-thirds of drugs stayed with NPs upon diffusion method. On the other hand, cellular uptake of Chl loaded BSA NPs caused a significant MCF7 breast cancer cell death, whereas free Chl and unloaded BSA NPs did not have a significant effect on the cell viability. Furthermore, in vivo toxicity assessment of BSA NPs obtained in the IL system was conducted in the zebrafish animal model. It showed that zebrafish body is able to eliminate BSA NPs without any toxic side effects and encapsulation of Chl into NPs reduced the toxicity of free Chl. In summary, we showed that BSA NPs with size smaller than 200 nm could be prepared in BmimCF3SO3 mediated system. They can be used for Chl loading (up to 6.9 wt%) with a sustainable release and they induce significant cell death in Chl sensitive cancer cells up to 45% in 24 h. These results indicate that BSA NPs could be prepared alternatively in IL systems and used in drug delivery studies.Article Citation - WoS: 45Citation - Scopus: 48Recrystallization and Grain Growth Kinetics of In718 Manufactured by Laser Powder Bed Fusion(Elsevier, 2022) Doğu, Merve Nur; Davut, Kemal; Obeidi, Muhannad Ahmed; Yalçın, Mustafa Alp; Gu, Hengfeng; Low, Thaddeus Song En; Ginn, Jon; Brabazon, DermotThe recrystallization and grain growth behaviour of IN718 alloy additively manufactured by laser powder bed fusion (L-PBF) is presented herein. The effects of three different temperatures (1050, 1150 and 1250 °C) and holding times (15, 45 and 90 min) were investigated. The texture evolution of the samples was recorded via electron backscatter diffraction (EBSD). The as-built sample is composed of bowl-shaped melt pools, a chessboard-like grain pattern and has a cube texture {100}<001>. Recrystallized grains were observed in the samples treated at 1150 °C for 15 min, as well as the samples treated for longer periods and at higher temperatures. Recrystallization was observed to start from high dislocation density regions, including the overlapping melt pools and the borders of the chessboard-like pattern. The initial cube texture transforms into a first-generation cube-twin texture {122}<212> via a twinning-assisted recrystallization mechanism. Then, those recrystallization nuclei sweep through the high defect density matrix; during which almost no new twins are formed. The samples treated at 1250 °C are almost completely recrystallized, which forms a weaker cube texture and a stronger P-orientation {011}<112>. However, the growth of recrystallized grains is very limited due to the presence of non-coherent precipitates.Article Citation - WoS: 10Citation - Scopus: 10An in Vivo Zebrafish Model Reveals Circulating Tumor Cell Targeting Capacity of Serum Albumin Nanoparticles(Elsevier, 2022) Çakan Akdoğan, Gülçin; Ersöz, Esra; Sözer, Sümeyra Çiğdem; Gelinci, EmineNanoparticles are promising tools of drug delivery in modern medicine. There is a need for fast and reliable models for in vivo validation of newly developed nanocarriers. Here, we report a fast and easy zebrafish larval model to study the biodistribution and cancer cell targeting capacity of serum albumin nanoparticles in vivo. Fluorescently tagged Bovine Serum Albumin Nanoparticles (BSA-NPs) delivered intravenously to the zebrafish larvae, can be used to study the biodistribution via live imaging. We showed that the BSA-NPs were instantly distributed to the larval vasculature including the brain, without causing any toxicity. The clearance of nanoparticles from the body occurred within few days, which gives sufficient time to study anti-cancer efficiency of the BSA-NPs. Next, we asked whether the BSA-NPs can target the cancer cells in circulation. We established a circulating tumor cell (CTC) xenograft model and described a quantitative method for colocalization and cancer cell death analysis in the intact live organism. We showed that BSA-NPs effectively found and localized to MCF7 cells in vasculature which were killed upon doxorubicin delivery. Interestingly, folic acid coating of BSA-NPs caused faster colocalization but did not increase the overall cell death. This is the first report of the biodistribution, toxicity and anti-cancer effectiveness of serum albumin-based nanoparticles in the zebrafish model. Moreover, here we report for the first time that BSA-NPs are able to target the CTCs in an in vivo model. The zebrafish CTC model and the analysis protocol reported here can be used to assess CTC targeting capacity of nanoparticles and devise patient specific CTC targeting tests.Article Citation - WoS: 9Citation - Scopus: 9Polymer-derived ceramic molten metal filters(Springer, 2022) Dizdar, Kerem Can; Kulkarni, Apoorv; Dışpınar, Derya; Soraru, Gian Domenico; Ahmetoğlu, Çekdar Vakıf; Semerci, TuğçeThis paper reports the synthesis and the performance of polymer-derived ceramic filters for molten metal filtration. Two different filter types were studied: foam filters produced from flexible polyurethane (PU) foams and additive manufacturing (AM) filters produced from thermoplastic polyurethane (TPU) cellular structure, and the results from all filter types were compared with that of the commercially used SiC foam filters. In both cases, the urethane-based polymeric template was impregnated with the preceramic solution, followed by pyrolysis. The produced ceramic components were then used to filter a molten Al alloy (A357), and the resulting Al samples were characterized for their mechanical properties. When filters were used, more reproducible and reliable mechanical properties were achieved compared to the samples obtained without any filtration. Among the different filters tested, the foam filters demonstrated better performance in comparison with the AM ceramic filters due probably to the three-dimensional interconnected porosity compared with the unidirectional cellular structure of the AM ceramic filters.Article Citation - WoS: 6Citation - Scopus: 6Tribocorrosion-Resistant Ti40nb-Tin Composites Havingtio(2)-Based Nanotubular Surfaces(American Chemical Society, 2022) Çaha, İhsan; Alves, Alexandra Cruz; Chirico, Caterina; Pinto, Ana Maria; Tsipas, Sophia; Gordo, Elena; Toptan, FatihA novel multifunctional material was developed byhard TiN particle reinforcement addition to a beta-type Ti40Nb alloy,followed by surface functionalization, yielding the formation of ananotubular layer. Corrosion and tribocorrosion behaviors wereinvestigated in a phosphate-buffered saline solution at bodytemperature. The results revealed that the Ti40Nb-TiNcomposites presented similaripassandE(i=0)values together withrelatively similarRoxandCox. However, its tribocorrosion resistancedrastically improved (wear volume is almost 15 times lower than anunreinforced alloy) as a consequence of the load-carrying effectgiven by the reinforcement phases. The corrosion and tribocorro-sion behaviors were further improved through surface functionaliza-tion as observed by significantly loweripassand higherRoxvalues andalmost undetectable wear volume loss from tribocorrosion tests dueto the formation of a well-adhered anatase-rutile TiO2-based nanotubular layer.Article Citation - WoS: 8Citation - Scopus: 8Design and Fabrication of Polymer Micro/Nano Composites With Two-Level Mechanical Reinforcing Procedure(Wiley, 2022) Kandemir, Ayşe Çağıl; Dönmez, Fatma; Davut, Kemal; Kaplan Can, HaticeBiocompatible composite production was accomplished by utilizing two-level hierarchical approach for mechanical reinforcement. A well-known commodity polymer; low-density polyethylene (LDPE), which has high-fracture toughness, yet low strength and modulus was used as the main matrix material. As the first step of hierarchy, ductile LDPE was blended with brittle polyvinylpyrrolidone (PVP), which is an eco-friendly, nontoxic and biocompatible polymer. This resulted in slight decrease of strength and drastic reduction of toughness (%70), yet modulus was increased by 78%. As the second level of hierarchy, PVP composites were introduced in LDPE. Nano-scaled Halloysite clay and micro-scaled spherical Silica particles were utilized as additives in the aforementioned PVP composites. The reason for the choice of these particles is that they are nontoxic, low-cost and in the case of Halloysite; abundant in nature. Owing to the implementation of the second level; modulus improvement was further enhanced to 150%, with additional benefits of strength increase up to 17% and less reduction in fracture toughness (minimum 51% reduction). Dynamic mechanical analysis also supported these outcomes that storage modulus of composites are higher than both LDPE and LDPE-PVP blend. The proposed biocompatible composites in the end of this study would be utilized in biomedical applications necessitating mechanical improvements.