WoS İndeksli Yayınlar Koleksiyonu / WoS Indexed Publications Collection
Permanent URI for this collectionhttps://hdl.handle.net/11147/7150
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Article Rice-Like, Hollow, and Rhombohedral Nano-Calcite Synthesis by Carbonization(Elsevier, 2026) Kilic, Sevgi; Toprak, Gorkem; Ozdemir, EkremControlling the morphology and size of calcium carbonate (CaCO3) remains an essential challenge in the production of high-performance fillers and advanced functional materials. Here, we report a continuous carbonization strategy that enables the synthesis of monodisperse nano-calcite particles with tunable rice-like, hollow, and rhombohedral morphologies through precise control of CO2 dissolution into a flowing Ca(OH)2 solution under diffusion-limited conditions. A two-stage reactor was designed to decouple nucleation and growth by separating the gas-liquid interaction zone from a stabilization tank. pH and conductivity analyses revealed that crystallization is primarily governed by the CO2 dissolution kinetics rather than mixing intensity in the stabilization tank. SEM and XRD analyses demonstrate a distinct crystallization sequence such that initial formation of rice-like calcite, subsequent development of hollow nanoparticles through selective tip dissolution, and final transformation into rhombohedral calcite via dissolution-reprecipitation mechanism. The method provides a reproducible, template-free route for fabricating hollow CaCO3 nanoparticles, overcoming limitations of bubbletemplating and additive-mediated techniques. This scalable process provides a robust foundation for producing high-surface-area CaCO3 nanomaterials which have potential applications in thin films, ceramics, protective coatings, lightweight composites, thermal/acoustic insulation, adsorption, and catalysis, where tailored particle morphology and size can significantly enhance performance.Article Advanced Hybrid Machine Learning for Precise Short-Term Drought Prediction: A Comparative Study of SPI and SPEI Indices in Iran's Arid and Semi-Arid Regions(Birkhauser, 2025) Talebi, H.; Citakoglu, H.; Samadianfard, S.; Erol, A.Drought has been viewed as a climatic event of significant importance that hampers agricultural productivity, efficient management of water resources, and socio-economic development, especially in arid, semi-arid, and arid-semiarid regions. Even though improved approaches to modeling dry spells have been reported, there remains a substantial disparity in the forecasting ability of the Standardized Precipitation Index (SPI) and the Standardized Precipitation Evapotranspiration Index (SPEI) for different climatic conditions. In response to the observed disparity, the current study utilized the Tuned Q-factor Wavelet Transform (TQWT), Variational Mode Decomposition, Empirical Mode Decomposition, and Empirical Wavelet Transform (EWT), together with Gaussian Process Regression (GPR), Support Vector Machines, and Adaptive Neuro-Fuzzy Inference System (ANFIS) models. The dataset included precipitation and temperature data collected from four synoptic instrument-equipped meteorological stations from 1990 to 2022—Tabriz and Shiraz corresponding to semi-arid, and Kerman and Yazd corresponding to arid regions—and included SPI and SPEI index predictions for temporal periods of 1, 3, and 6 months. Through the use of autocorrelation diagnostics, it was possible to identify the optimal input lags (t-1, t-2, and t-3) specifically allocated for the model development process, derived from 75% of the available dataset. For the case of the 1-month temporal period, the models using the TQWT revealed the best forecasting effectiveness; most importantly, the TQWT-ANFIS model recorded the highest accuracy at the Tabriz station, while the TQWT-GPR model showed the highest accuracy values at Shiraz, Kerman, and Yazd (R2≈0.996–0.997; RMSE≈0.05–0.07). For the 3- and 6-month temporal evaluations, the EWT-ANFIS model recorded the best performance among all allocated stations, marked by the lowest error metrics (RMSE≈0.01–0.03) together with nearly perfect goodness-of-fit values (R2 and NSE≈0.999). The Shiraz and Kerman observation stations showed the best performance indices, reaching a Kling-Gupta Efficiency (KGE) of 0.99. By comparison, the report from Tabriz indicated a poorer KGE of about 0.93, while the Yazd station showed volatility in the 6-month Standardized Precipitation Index, reaching a KGE of about 0.60, suggesting a rising aridity trend. Overall, results demonstrate that while TQWT-based models dominate short-term drought prediction, EWT-ANFIS is the most robust for medium- and long-term forecasts. These findings emphasize the potential of hybrid decomposition–machine learning frameworks to improve drought monitoring and strengthen water resource management strategies in water-scarce regions. © The Author(s), under exclusive licence to Springer Nature Switzerland AG 2025.Article Design, Synthesis, and Evaluation of Anticancer Activities of 1,2-Diborolane Derivatives for Hepatocellular Carcinoma: an in Vitro and in Silico Study(Elsevier, 2026) Sahin, Yuksel; Antika, Gizem; Aktan, Cagdas; Metin, Kubilay; Ozgener, HuseyinHepatocellular carcinoma (HCC) is the most prevalent form of primary liver cancer and remains a major global health challenge due to limited treatment options and poor prognosis. Boron-containing compounds have garnered attention for their diverse biological activities, including pro-apoptotic effects in various types of cancer. In this study, we synthesized a panel of novel 1,2-N-substituted-1,2-diborolane derivatives and evaluated their antiproliferative, antimigratory, and apoptotic effects on hepatocellular carcinoma cell lines, HepG2 and Hep3B. Spectroscopic analyses confirmed the structural integrity of the synthesized compounds, revealing characteristic 1H-, 11B-, and 13C-NMR shifts consistent with boron-oxygen and boron-nitrogen bonding patterns. The derivatives, particularly compounds 2, 3, and 6, demonstrated potent and selective cytotoxicity toward HCC cells, with compound 3 exhibiting the lowest IC50 value (6.75 mu M) in HepG2 cells. Their time-dependent anti-proliferative effects were further supported by colony formation assays demonstrating long-term growth suppression, while wound healing assays revealed marked inhibition of HepG2 cell migration, indicating the compound's anti-metastatic potential. Our results demonstrate that the compound significantly induces apoptosis, modulates the expression of key apoptotic genes (Bax, Bcl-2, and caspase-3). In silico molecular docking further confirmed strong binding affinity to the anti-apoptotic Bcl-2 protein, supporting the proposed mechanism of action. These findings highlight the compound as a promising candidate for further preclinical evaluation in liver cancer therapy.Article Digital <i>h</I>-fibrations and Some New Results on Digital Fibrations(Mdpi, 2024) Termen, Talip Can; Ege, OzgurIn this work, the notion of digital fiber homotopy is defined and its properties are given. We present some new results on digital fibrations. Moreover, we introduce digital h-fibrations. We prove some of the properties of these digital h-fibrations. We show that a digital fibration and a digital map p are fiber homotopic equivalent if and only if p is a digital h-fibration. Finally, we explore a relation between digital fibrations and digital h-fibrations.Article Citation - WoS: 6Citation - Scopus: 6Biomolecular Fingerprints of the Effect of Zoledronic Acid on Prostate Cancer Stem Cells: Comparison of 2d and 3d Cell Culture Models(Academic Press Inc., 2024) Güler,G.; Acikgoz,E.; Mukhtarova,G.; Oktem,G.Revealing the potential of candidate drugs against different cancer types without disrupting normal cells depends on the drug mode of action. In the current study, the drug response of prostate cancer stem cells (PCSCs) to zoledronic acid (ZOL) grown in two-dimensional (2D) and three-dimensional (3D) culture systems was compared using Fourier transform-infrared (FT-IR) spectroscopy which is a vibrational spectroscopic technique, supporting by biochemical assays and imaging techniques. Based on our data, in 2D cell culture conditions, the ZOL treatment of PCSCs isolated according to both C133 and CD44 cell surface properties induced early/late apoptosis and suppressed migration ability. The CD133 gene expression and protein levels were altered, depending on culture systems. CD133 expression was significantly reduced in 2D cells upon ZOL treatment. FT-IR data revealed that the integrity, fluidity, and ordering/disordering states of the cell membrane and nucleic acid content were altered in both 2D and 3D cells after ZOL treatment. Regular protein structures decrease in 2D cells while glycogen and protein contents increase in 3D cells, indicating a more pronounced cytotoxic effect of ZOL for 2D cells. Untreated 3D PCSCs exhibited an even different spectral profile associated with IR signals of lipids, proteins, nucleic acids, and glycogen in comparison to untreated 2D cells. Our study revealed significant differences in the drug response and cellular constituents between 2D and 3D cells. Exploring molecular targets and/or drug-action mechanisms is significant in cancer treatment approaches; thus, FT-IR spectroscopy can be successfully applied as a novel drug-screening method in clinical research. © 2024 Elsevier Inc.Article Citation - WoS: 5Citation - Scopus: 5Effects of Diborolane Containing Oxo/Amine Compounds on Clinically Important Bacteria and Candida Species(Elsevier B.V., 2024) Şahin,Y.; Çoban,E.P.; Özgener,H.; Bıyık,H.H.; Sevincek,R.; Aygün,M.; Gürbüz,B.A good yield of 1,2-diborolanderivatives 2-8 was obtained from the reaction of 1,2-dichloro-1,2-diborolane 1 and R2NLi/ArNHLi/PhOLi/H2O. The structures of these new derivatives were characterized by nuclear magnetic resonance spectroscopy. The molecular structures of 4 and 7a were also determined using single-crystal X-ray diffraction. The antimicrobial activities of synthesized compounds were tested against clinically important Gram-positive, Gram-negative bacteria, and Candida species. The most effective substances were found to be compounds 2, 3, 4, 6 and 8 among the tested compounds. Therefore, the activity of these substances were investigated against Staphylococcus aureus ATCC 43300 and Enterococcus faecalis ATCC 51575, which form biofilms and have antibiotic resistance. Compound 2, 6 and 8 appears to be a promising candidate for potential antibacterial agents against these bacterial strains, especially given its potent activity against biofilm-forming and antibiotic resistant strains. The results indicate that these new materials will be evaluated as potential drugs against infectious diseases in the future. © 2024 Elsevier B.V.Article Citation - WoS: 5Citation - Scopus: 6Undescribed Polyether Ionophores From Streptomyces Cacaoi and Their Antibacterial and Antiproliferative Activities(Elsevier, 2022) Gezer, Emre; Üner, Göklem; Küçüksolak, Melis; Kurt, Mustafa Ünver; Doğan, Gamze; Ballar Kırmızıbayrak, Petek; Bedir, ErdalPolyether ionophores represent a large group of naturally occurring compounds mainly produced by Streptomyces species. With previously proven varieties of bioactivity including antibacterial, antifungal, antiparasitic, antiviral and anti-tumor effects, the discovery of undescribed polyethers leading to development of efficient therapeutics has become important. As part of our research on polyether-rich Streptomyces cacaoi, we previously performed modification studies on fermentation conditions to induce synthesis of specialized metabolites. Here, we report four undescribed and nine known polyether compounds from S. cacaoi grown in optimized conditions. Antimicrobial activity assays revealed that four compounds, including the undescribed (6), showed strong inhibitory effects over both Bacillus subtilis and methicillin-resistant Staphylococcus aureus (MRSA) growth. Additionally, K41-A and its C15-demethoxy derivative exhibited significant cytotoxicity. These results signified that selectivity of C15-demethoxy K41-A towards cancer cells was higher than K41-A, which prompted us to conduct mechanistic experiments. These studies showed that this uninvestigated compound acts as a multitarget compound by inhibiting autophagic flux, inducing reactive oxygen species formation, abolishing proteasome activity, and stimulating ER stress. Consequently, the optimized fermentation conditions of S. cacaoi led to the isolation of undescribed and known polyethers displaying promising activities.Article Military Intelligence Deeds in the Reports of Izmir British Consulate General (1878-1914)(Ege Univ, 2011) Aditatar, FundaFrom 1825 up to the late nineteenth century the British Levant Consular Service developed highly parallel with the policy of Britain in the Ottoman Empire. During the protection policy of the Ottoman territory which continued until the 1870s, political and commercial aspects of consular services has been formulated almost an equal level. Instead of protecting the territorial integrity of the Empire after the Berlin Treaty of 1878 turned into a controlled sharing and consuls began press to served heavily political direction. The aim of this paper is to evaluate reports of Izmir British Consulate about military intelligence. The voluminous reports of the consulate related with the military intelligence. This situation occurs in Izmir because of commercial importance and strategic location, and also riots and wars all of these can be explained in the intensive military mobility during the last period of the Empire (1878-1914).Article Citation - WoS: 29Citation - Scopus: 33Areally-Averaged Overland Flow Equations at Hillslope Scale(Taylor and Francis Ltd., 1998) Tayfur, Gökmen; Kavvas, M. LeventMicroscale-averaged inter-rill area sheet flow and rill flow equations (Tayfur and Kavvas, 1994) are averaged along the inter-rill area length and rill length to obtain local areally-averaged inter-rill area sheet flow and rill flow equations (local-scale areal averaging). In this averaging, the local areally-averaged flow depths are related to the microscale-averaged flow depths at the outlet sections (downstream ends) of a rill and an inter-rill area by the assumption that the flow in these sections has the profile of a sine function. The resulting local areally-averaged flow equations become time dependent only. To minimize computational efforts and economize on the number of model parameters, local areally-averaged flow equations are then averaged over a whole hillslope section (hillslope-scale areal averaging). The expectations of the terms containing more than one variable are obtained by the method of regular perturbation. Comparison of model results with observed data is satisfactory. The comparison of the model results with those of previously developed models which use point-scale and large-scale (transectionally) averaged technology indicates the superiority of this model over them. Microscale-averaged inter-rill area sheet flow and rill flow equations (Tayfur & Kavvas, 1994) are averaged along the inter-rill area length and rill length to obtain local areally-averaged inter-rill area sheet flow and rill flow equations (local-scale areal averaging). In this averaging, the local areally-averaged flow depths are related to the microscale-averaged flow depths at the outlet sections (downstream ends) of a rill and an inter-rill area by the assumption that the flow in these sections has the profile of a sine function. The resulting local areally-averaged flow equations become time dependent only. To minimize computational efforts and economize on the number of model parameters, local areally-averaged flow equations are then averaged over a whole hillslope section (hillslope-scale areal averaging). The expectations of the terms containing more than one variable are obtained by the method of regular perturbation. Comparison of model results with observed data is satisfactory. The comparison of the model results with those of previously developed models which use point-scale and large-scale (transectionally) averaged technology indicates the superiority of this model over them