DSpace Arşivi :: Ana Sayfa

İstanbul Gelişim Üniversitesi Kurumsal Açık Erişim Arşivi

DSpace@Gelişim, İstanbul Gelişim Üniversitesi tarafından doğrudan ve dolaylı olarak yayınlanan; kitap, makale, tez, bildiri, rapor, araştırma verisi gibi tüm akademik kaynakları uluslararası standartlarda dijital ortamda depolar, Üniversitenin akademik performansını izlemeye aracılık eder, kaynakları uzun süreli saklar ve yayınların etkisini artırmak için telif haklarına uygun olarak Açık Erişime sunar.

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Identifying the optimal flexural performance of metal-composite single-lap joints with copolyester-reinforced epoxy adhesive under various loading rates using the Grey Relation Analysis
(ELSEVIER SCI LTD, 125 London Wall, London EC2Y 5AS, ENGLAND, 2026) Erbayrak, Engin; Erbayrak, Seda; Eker, Beril; Çolak, Murat
This study examines the best flexural performance of metal composite single-lap joints fabricated with copolyester-reinforced epoxy adhesives at various loading rates using the Grey Relation Analysis (GRA). The study consists of three parts. The first part involves the formation of metal composite single-lap joints and their experimental approach under different loading rates. In the experimental approach, A356 aluminum was used as the metal material with the addition of titanium (Ti) and boron (B) additives. Plain-woven glass fiber-reinforced epoxy (GFRE) and plain-woven carbon fiber-reinforced epoxy (CFRE) were served as the composite materials. The lap joints were tested in three-point bending tests under loading rates of 1, 10, and 50 mm/min, respectively. In the second part, a numerical analysis was conducted using boundary conditions similar to the experimental conditions. In the numerical analysis, a 6-node pentahedral cohesive element was utilized, representing a novel approach for modeling adhesives in finite element analysis (FEA). When experimental and numerical results were compared, a difference of 4.36% was observed between the maximum load values and 6.80% between the failure displacements. Based on these results, it can be said that the experimental results converge with the numerical results. In the last part of the study, performance rankings of metal composite joints were determined using the Grey Relational Analysis (GRA) method, which enabled us to identify the optimum joint. This systematic approach facilitated the scientific design of joints that demonstrate optimal flexural performance under various loading conditions.
Crystal structure, morphology, magnetic, electrical, and dielectric characterization of amphoteric Yb2O3-modified lead-free BaTiO3 perovskite
(ACADEMIC PRESS LTD- ELSEVIER SCIENCE LTD, 24-28 OVAL RD, LONDON NW1 7DX, ENGLAND, 2026) Slimani, Yassine; Ünal, Bayram; Baykal, Abdulhadi; Thakur, Atul
Large-scale perovskite applications require a lead-free matrix with tolerable properties. Rare earth doping can be an effective way to achieve an enhanced performance. While previous studies have primarily focused on low rare-earth doping levels, research into reaching the maximum solubility limit of the guest rare earth into the perovskite host is still notably sparse. This work investigates the structural, morphological, magnetic, electrical, and dielectric properties of leadfree BaTiO3 (BTO) perovskite ceramic modified with high weight fractions (2–20 wt%) of amphoteric Yb2O3. X-ray diffraction (XRD) analysis revealed a composite-like microstructure where Yb2O3 persists as a separate phase across all concentrations, while the host lattice exhibited an oscillatory volume response, highlighting the amphoteric transition of Yb3+ ions between A and B sites. Scanning electron microscopy and energy-dispersive X-ray spectroscopy (SEM/EDX) mapping revealed typical quasi-spherical and polyhedral BTO grains alongside irregular Yb2O3 precipitates. The magnetization versus applied magnetic field (M(H)) analysis showed hysteresis loops, reflecting ferromagnetic behavior of the samples, likely governed by the bound magnetic polaron (BMP) model. The electrical and dielectric properties of BaTiO3/xYb2O3 ceramics were also systematically examined over a temperature range from 20 ◦C to 120 ◦C. AC conductivity exhibits characteristic dispersive behavior tracking universal Jonscher power law (UJPL), confirming a thermally activated hopping conduction explained by the correlated barrier hopping (CBH) model. The frequency exponent (0 ≤ s ≤ 1) reduces with rising temperature, indicating enhanced charge-carrier mobility. DC conductivity obeys Arrhenius performance, with the activation energy greatly dependent on additive concentration; moderate Yb2O3 contents (2–10 wt%) improve charge transport, while higher concentrations stimulate defect-induced carrier trapping. A pronounced reduction in dielectric constant (from ~1500 to ~5–20) is observed due to the construction of a composite microstructure and dominance of ferroelectric polarization. In the meantime, the dielectric loss and dissipation factor are significantly diminished. Impedance analysis reveals non-Debye relaxation, dominated by grain-boundary and interfacial effects. These findings demonstrate that Yb2O3 modification and composite formation provide an effective strategy for tailoring the electrical performance of BaTiO3 ceramics for advanced dielectric applications.
New thiophene pyrazole hybrid: An efficient synthesis, X-ray analysis, computational and in silico studies
(ELSEVIER, RADARWEG 29, 1043 NX AMSTERDAM, NETHERLANDS, 2026) Bin Muhsinah, Abdullatif; Kheder, Nabila A.; Elhaty, Ismail A. M.; Mahmoud, Naglaa S.; Mabkhot, Yahia N.
A one-pot, three-component synthesis of ethyl 5-(3-ethoxy-3-oxopropanoyl)-4-phenyl-2-(phenylamino)thiophene-3-carboxylate (7) was reported. Its reaction with DMF-DMA and phenylhydrazine produced a thiophene pyrazole hybrid 8. The chemical structures of the synthesized compounds were confirmed using spectral (IR, NMR, MS) and elemental analysis. Additionally, the 3D structure of compound 8 was confirmed by single-crystal X-ray diffraction. The crystallographic study revealed that compound 8 is mainly stabilized by weak C–H•••O and C–H•••N contacts together with dispersive interactions. Hirshfeld surface analysis revealed that crystal packing is dominated by H•••H (57.9%), C•••H (18.6%), and O•••H (10.6%) interactions. DFT calculations for compounds 7 and 8 support experimental interpretation. MEP surface showed that carbonyl oxygen atoms are the richest regions, while FMO analysis indicated moderate HOMO/LUMO gaps (4.032 for 7 and 4.125 eV for 8), consistent with a stable and polarizable conjugated system. NBO and Mulliken charge analyses are consistent with MEP results. In silico ADME prediction was performed to evaluate the physicochemical and pharmacokinetic properties of the synthesized compounds. Molecular docking studies were conducted against the EGFR protein (PDB ID: 5UGB) to investigate their potential as anticancer leads. The results revealed that compound 7 exhibited the most favorable predicted binding activity, while both compounds demonstrated binding patterns and affinities comparable to the reference drug.
Integrated Wind-Solar-LNG system for green liquefied hydrogen and multi-energy supply: Techno-Economic-Environmental analysis and data-driven ANN-GA optimization
(ELSEVIER SCI LTD, 125 London Wall, London EC2Y 5AS, ENGLAND, 2026) Ji, Ling; Basem, Ali; Balla, Hyder H. Abed; Alkhatib, Omar J.; Alkhattabi, Khalid; Li, Yonghui; Ahmed, M. A.; Alanazi, Mohana; Albalawi, Hind; Mahariq, Ibrahim
The production of low-carbon hydrogen fuel is critical for sustainable energy systems. This study proposes a centralized district-scale wind–solar cogeneration system designed to generate green liquefied hydrogen alongside electricity, cooling, and freshwater for zero-emission building clusters. The system couples a wind farm and parabolic trough solar collectors with an LNG regasification unit, steam and organic Rankine cycles, an absorption refrigeration cycle, a thermoelectric generator, a reverse osmosis desalination plant, a proton exchange membrane electrolyzer, and a Claude-based hydrogen liquefaction cycle. LNG cold energy is strategically utilized to enhance hydrogen liquefaction efficiency, reduce refrigeration energy demand, and maximize overall exergy utilization. Cascaded thermal integration among power, cooling, and hydrogen subsystems further improves waste-heat recovery and system performance. A comprehensive energy, exergy, economic, and environmental assessment is conducted, and multi-objective optimization using NSGA-II, assisted by an artificial neural network surrogate model (MSE = 0.00681), substantially reduces computational time while maintaining high accuracy. Under optimal conditions, the system achieves an exergy efficiency of 21.25%, producing 4.19 kg/h of liquefied hydrogen as a green fuel, 1.39 MW of net electricity, and freshwater and cooling at a 29.6% lower total cost rate relative to the baseline. A case study for Dammam, Saudi Arabia, demonstrates the system’s potential as a scalable, low-carbon, integrated energy–water–fuel solution in hot-arid climates.
Ethyl 4-methyl-2-(phenylamino)thiophene-3-carboxylate: One-pot synthesis, structural characterization, computational studies, and antitumor activity
(ELSEVIER, RADARWEG 29, 1043 NX AMSTERDAM, NETHERLANDS, 2026) Bin Muhsinah, Abdullatif; Kheder, Nabila A.; Soliman, Saied M.; Elhaty, Ismail A. M.; Mabkhot, Yahia N.
Ethyl 4-methyl-2-(phenylamino)thiophene-3-carboxylate (8) was synthesized via a one-pot three-component reaction of ethyl 3-oxobutanoate, PhNCS, and 1-chloropropan-2-one in NaOEt. This process offers several advantages over previously reported synthetic method, including high yield, less reaction time and availability of the starting materials. Spectral data and X-ray analysis were used to elucidate the structure. Its structure is stabilized by a strong intramolecular N–H…O hydrogen bond. Hirshfeld analysis indicated the most dominant non-covalent interactions are C…H (26.3 %) and H…H (53.9 %), where the C11…H2 (2.760 Å) and C7…C7 (3.314 Å) contacts are the shortest contacts. In addition, DFT-based computational studies were performed to assess the electronic structure and local reactivity of thiophene 8. HOMO–LUMO energy gaps, MEP surface mapping, Mulliken charge distribution, and Fukui function analyses were used to identify the key electrophilic and nucleophilic centers within the molecules. Antitumor activity of thiophene 8 was assessed against HepG2 (liver cancer), MCF-7 (breast cancer), and HCT116 (colorectal cancer) by means of the sulforhodamine B (SRB) assay. The compound exhibited promising anticancer activity, showing its highest potency against HepG2 (IC50 =40.1 ± 1.3 μg/mL) compared to MCF-7 (76.3 ± 2.5) and HCT-116 (92.9 ± 2.02 μg/mL) cell lines.