WoS İndeksli Yayınlar Koleksiyonu

Permanent URI for this collectionhttps://hdl.handle.net/20.500.12573/394

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Citation - WoS: 6
Citation - Scopus: 6
3-Sulfopropyl Methacrylate Based Cryogels as Potential Tissue Engineering Scaffolds
(Taylor & Francis Ltd, 2020) Durukan, Adile Yuruk; Isoglu, Ismail Alper
In this study, we developed cryogels containing 3-sulfopropyl methacrylate (SPMA) and 4-vinyl pyridine (4-VP) as a potential scaffold for tissue engineering applications. Cryogels with varying monomer ratios were synthesised by chemical cross-linking under cryogelation conditions. Effect of initiators and cross-linker amount (0.025-0.15 g MBA; 0.012-0.05 g APS; 2.5-12.5 mu l TEMED) and also freezing temperature (-20 and -80oC) were investigated, and the conditions were optimised according to the morphological structures examined by SEM. The functional groups of the materials were characterised by FT-IR. Compression test and swelling were applied to investigate mechanical properties and water absorption ability, respectively. As a preliminary study, selected materials were tested for cell cytotoxicity with MTT. According to our results, the ionic and biocompatible cryogels prepared in this study possessing a highly porous and interconnective structure with good mechanical characteristics and swelling properties can be suitable as tissue scaffolds for many applications.
Citation - WoS: 2
Citation - Scopus: 1
94.8 Km-Range Direct Detection Fiber Optic Distributed Acoustic Sensor
(Optica Publishing Group (Formerly OSA), 2019) Uyar, F.; Onat, T.; Unal, C.; Kartaloǧlu, T.; Ozdur, I.; Özbay, E.
This work demonstrates an ultra-long range direct detection fiber optic distributed acoustic sensor which can detect vibrations at a distance of 94.8 km with 10 m resolution along the sensing fiber. © 2023 Elsevier B.V., All rights reserved.
Citation - WoS: 2
Citation - Scopus: 3
94.8 Km-Range Direct Detection Fiber Optic Distributed Acoustic Sensor
(Institute of Electrical and Electronics Engineers Inc., 2019) Uyar, Faruk; Onat, Talha; Unal, Canberk; Kartaloǧlu, Tolga; Ozdur, Ibrahim T.; Özbay, Ekmel
This work demonstrates an ultra-long range direct detection fiber optic distributed acoustic sensor which can detect vibrations at a distance of 94.8 km with 10 m resolution along the sensing fiber. © 2019 Elsevier B.V., All rights reserved.
A Comprehensive Analysis of Acoustic Emission Signals To Distinguish the Different Damage Types for Fiber-Reinforced Polymers: A Review
(Wiley, 2025) Yilmaz, Cagatay
Fiber-reinforced polymers (FRP) attract the attention of key industries, such as aerospace, wind energy, and automotive, as they can reduce the weight of structural components without compromising their mechanical properties. Due to FRP's anisotropic and non-homogeneous structure, their failure under different loading conditions and the corresponding failure mechanisms must be investigated. One method that progressively monitors the failure of FRP underload is Acoustic Emission (AE). AE can register the elastic stress waves in the form of digitized waveforms, released by the discontinuous events that occur in the FRP under load. These discontinuities can be clustered and identified as transverse cracking, fiber/matrix interface debonding, delamination, and fiber failure by analyzing the AE waveforms. Recently, numerous clustering approaches using machine learning algorithms, along with the varying features of AE waveforms, have been developed and are being used. These algorithms include supervised and unsupervised clustering, deep learning algorithms, and neural network methods, among others. While supervised algorithms require a training dataset to classify AE signals, unsupervised algorithms can perform clustering without training datasets. Deep learning and neural network algorithms can train themselves to cluster data, but they may require a significant amount of computer power when the dataset is large. This review paper provides comprehensive information on the clustering algorithm, along with the AE wave features, the range of features for different damage types, and the type of reinforcer.
A Comprehensive Review on the Extraction and Recovery of Lithium from Primary and Secondary Sources: Advances Toward Battery-Grade Materials
(Wiley, 2025) Top, Soner; Kursunoglu, Sait; Altiner, Mahmut
Lithium-ion battery (LIB) technologies have become indispensable to modern energy systems, driving global demand for high-purity lithium compounds. This review focuses on lithium recovery and purification strategies for battery-grade lithium carbonate (Li2CO3) and lithium hydroxide (LiOH), addressing both primary sources (brines and minerals) and secondary sources (waste materials). Industrially established processes, such as evaporation-based brine treatment and conventional metallurgical methods, are discussed alongside emerging techniques, including membrane separation, solvent extraction, and CO2-assisted precipitation. Particular attention is given to lithium precipitation mechanisms, the behaviour of co-existing ions during extraction, and the specific quality requirements for cathode material synthesis. By evaluating process scalability, environmental impact, and product purity, this review provides a comprehensive understanding of current practices and future directions. Additionally, it highlights the growing importance of lithium in the context of accelerating electric vehicle (EV) adoption, underscoring the bright and expanding future of the lithium industry.
Citation - WoS: 3
Citation - Scopus: 3
Ab Initio Simulation of Amorphous BC3
(Elsevier, 2020) Durandurdu, Murat
We report the structural and electrical properties of an amorphous BC3 model based on ab initio molecular dynamics simulations. The amorphous network is achieved from the melt and has a layer-like structure consisting of mainly hexagonal (six membered) rings as in the crystal. However, the distribution of boron atoms in the noncrystalline configuration appears to differ significantly from that of boron atoms in the crystal. The network is a solid solution and has randomly distributed nanosized graphene-like domains at each layer. Boron atoms have a tendency to form more overcoordinated defects involving with boron-boron homopolar bond(s). The mean coordination of boron and carbon atoms is 3.2 and 3.0, respectively. Interestingly the amorphous configuration is found to have a slightly higher density and bulk modulus than the crystal, which are attributed to the existence of overcoordinated units in the amorphous state. Based on the localization of the band tail states, noncrystalline BC3 is speculated to be a semiconducting material.
Citation - WoS: 3
Citation - Scopus: 2
Ab Initio Study of Boron-Rich Amorphous Boron Carbides
(Wiley, 2023) Yildiz, Tevhide Ayca; Durandurdu, Murat
Amorphous boron carbide compositions having high B contents (BxC1-x, 0.50 <= x <= 0.95) are systematically created by way of ab initio molecular dynamics calculations, and their structural, electrical, and mechanical characteristics are inclusively investigated. The coordination number of both B and C atoms increases progressively with increasing B/C ratio and more close-packed materials having pentagonal pyramid motifs form. An amorphous diamond-like local arrangement is found to be dominant up to 65% B content, and beyond this content, a mixed state of amorphous diamond- and B-like structures is perceived in the models because sp(3) hybridization around C atoms is still leading one for all compositions. The pentagonal pyramid motifs around C atoms are anticipated to appear beyond 65% content. The intericosahedral linear C-B-C chains do not form in any model. All amorphous boron carbides are semiconducting materials. The mechanical properties gradually increase with increasing B concentration, and some amorphous compositions are proposed to be hard materials on the basis of their Vickers hardness estimation.
Citation - WoS: 6
Citation - Scopus: 6
Absorption Enhancement by Semi-Cylindrical Structures for an Organic Solar Cell Application
(Optical Soc Amer, 2020) Hah, Dooyoung
Organic solar cells are attractive for various applications with their flexibility and low-cost manufacturability. In order to increase their attractiveness in practice, it is essential to improve their energy conversion efficiency. In this work, semi-cylindrical-shell-shaped structures are proposed as one of the approaches, aiming at absorption enhancement in an organic solar cell. Poly(3-hexylthiophene-2,5-diyl) blended with indene-C60 bisadduct (P3HT:ICBA) is considered as the active layer. Light coupling to the guided modes and a geometrical advantage are attributed to this absorption enhancement. Finite-difference time-domain methods and finite element analysis are used to examine the absorption spectra for two types of devices, i.e., a debossed type and an embossed type. It is shown that absorption enhancement increases as the radius of the cylinder increases, but reaches a saturation at about 4-mu m radius. The average absorption enhancement with an active layer thickness of 200 nm and radius of 4 mu m, and for incidence angles between 0 degrees and 70 degrees, is found as 51%-52% for TE-polarized input and as 30%-33% for TM-polarized input when compared to a flat structure. Another merit of the proposed structures is that the range of incidence angles where the integrated absorption is at the level of the normal incidence is significantly broadened, reaching 70 degrees-80 degrees. This feature can be highly useful especially when organic solar cells are to be placed around a round object. The study results also exhibit that the proposed devices bear broadband absorption characteristics. (C) 2020 Optical Society of America
Citation - WoS: 5
Citation - Scopus: 4
Active Subnetwork Ga: A Two Stage Genetic Algorithm Approach to Active Subnetwork Search
(Bentham Science Publ Ltd, 2017) Ozisik, Ozan; Bakir-Gungor, Burcu; Diri, Banu; Sezerman, Osman Ugur
Background: A group of interconnected genes in a protein-protein interaction network that contains most of the disease associated genes is called an active subnetwork. Active subnetwork search is an NP-hard problem. In the last decade, simulated annealing, greedy search, color coding, genetic algorithm, and mathematical programming based methods are proposed for this problem. Method: In this study, we employed a novel genetic algorithm method for active subnetwork search problem. We used active node list chromosome representation, branch swapping crossover operator, multicombination of branches in crossover, mutation on duplicate individuals, pruning, and two stage genetic algorithm approach. The proposed method is tested on simulated datasets and Wellcome Trust Case Control Consortium rheumatoid arthritis genome-wide association study dataset. Our results are compared with the results of a simple genetic algorithm implementation and the results of the simulated annealing method that is proposed by Ideker et al. in their seminal paper. Results and Conclusion: The comparative study demonstrates that our genetic algorithm approach outperforms the simple genetic algorithm implementation in all datasets and simulated annealing in all but one datasets in terms of obtained scores, although our method is slower. Functional enrichment results show that the presented approach can successfully extract high scoring subnetworks in simulated datasets and identify significant rheumatoid arthritis associated subnetworks in the real dataset. This method can be easily used on the datasets of other complex diseases to detect disease-related active subnetworks. Our implementation is freely available at https://www.ce.yildiz.edu.tr/personal/ozanoz/file/6611/ActSubGA.
Adaptive Re-Use of Medieval Caravanserais in Central Anatolia
(Gangemi Editore S P A, 2019) Yoney, Nilufer Baturayolu; Asiliskender, Burak; Urfalioglu, Nur
Kayseri, located at the junction of two major trade routes from northeast to southwest and from southeast to northwest, has been a commercial center for at least 4,000 years. The 23,500 tablets found at the Assyrian trade colony in Kanesh-Karum dating around 2,000 BCE and located 20km from the modern city provide ample proof. The great number and relevant size of Medieval caravanserais around the city as well as commercial buildings at the center indicate that this importance continued. Some of these caravanserais are already in use, albeit with inadequate architectural preservation measures while others are abandoned and/or partially destroyed. Indeed, the preservation, restoration and adaptive re-use of Medieval buildings is a major problematic, bringing out issues and interventions related to lacunae and reintegration, liberation or clearance of additions, structural strengthening with traditional/contemporary technologies, partial reconstruction, consolidation, cleaning and conservation of original building materials, and preventive maintenance. This paper aims to consider the possible presentation and adaptive re-use of Seljukid caravanserais over and inventory of accessible and at least partially preserved examples, focusing on eight case studies from the late 12th and 13th centuries: Karatay Han (1240), Tuzhisar Sultan Han (1232-1236), Eshab-i Kehf Han (before 1235), Cirgalan Han, Saruhan, Agzikarahan (1231-1240), Alayhan and Oresin Han.
Citation - WoS: 1
Citation - Scopus: 1
Addressing the Modern Regimes of Urban Spectacle: Revisiting the Ottoman General Exhibition of 1863 in Istanbul
(Sage Publications inc, 2024) Tozoglu, Ahmet Erdem
One of the most spectacular events of the Ottoman experience of modernity was the inauguration of the Ottoman General Exposition in Istanbul in 1863. The ancient Hippodrome, which is one of the most prominent venues of the city and the setting of memorable celebrations and festivals for centuries, hosted the event and provided the visitors with the opportunity to become part of the modern regimes of gaze and spectacle. This article posits three observer roles to reveal the multilayered structure of urban spectacle in mid-century Istanbul, namely the sultanic gaze, spectacle of the ordinary citizens, and the mediated experience of the foreigner. To understand the particularities of each position, I utilize several visual and textual documents about the exhibition event. Though just a single case in Ottoman urban history, the exposition enables us to understand how the new manner of modern urban spectacle emerged during a spectacular public event in Istanbul.
Citation - WoS: 6
Citation - Scopus: 5
Admissible Invariants of Genus 3 Curves
(Springer Heidelberg, 2015) Cinkir, Zubeyir
Several invariants of polarized metrized graphs and their applications in Arithmetic Geometry are studied recently. In this paper, we explicitly calculated these admissible invariants for all curves of genus 3. We find the sharp lower bound for the invariants phi, lambda and epsilon for all polarized metrized graphs of genus 3. This improves the lower bound given for Effective Bogomolov Conjecture for such curves.
Adult Zebrafish Brain as a Demyelination Model and Role of WNF Signaling in Remyelination
(Wiley, 2024) Bora, U.; Demirbasoglu, E. S.; Turhanlar-Sahin, E.; Guner, H.; Ozhan, G.
Citation - WoS: 4
Citation - Scopus: 4
Advanced Hybrid Machine Learning Methods for Predicting Rainfall Time Series: The Situation at the Kütahya Station in Türkiye
(Springer Heidelberg, 2025) Ilkentapar, Mucella; Citakoglu, Hatice; Talebi, Hamed; Akturk, Gaye; Spor, Pinar; Caglar, Yasin; Aksit, Serhat
Long-term variations in rainfall patterns, known as rainfall variability, have increasingly impacted ecological and socioeconomic systems, particularly in regions with high sensitivity. Consequently, accurate forecasting of rainfall at both short- and long-term time scales is essential, necessitating a comprehensive analysis of historical rainfall time series data collected from meteorological stations. In this study, K & uuml;tahya Province was selected as the study area, utilizing monthly rainfall data from its sole meteorological station spanning the period from 1960 to 2023. The dataset was partitioned into a training set (January 1960-March 2008) and a test set (April 2008-December 2023). Lagged rainfall values at t-1, t-2, and t-3 were used as input variables to predict rainfall at time t. The primary objective of this research is to assess the effectiveness of various preprocessing techniques in developing hybrid machine learning models for rainfall prediction. Gaussian Process Regression (GPR), Support Vector Machines, and Adaptive Neuro-Fuzzy Inference System were employed as machine learning methods. Furthermore, multiple signal decomposition techniques, including Complete Ensemble Empirical Mode Decomposition (CEEMD), Tunable Q-Factor Wavelet Transform, Empirical Mode Decomposition, Robust Empirical Mode Decomposition, Variational Mode Decomposition, Empirical Wavelet Transform, and Ensemble Empirical Mode Decomposition (EEMD), were utilized as preprocessing steps to enhance model performance. The predictive performance of the developed hybrid models was evaluated using various statistical measures. Among the evaluated models, the CEEMD-GPR hybrid model exhibited the best prediction performance with Coefficient of Determination (R2 = 0.998) and Nash-Sutcliffe Efficiency (NSE = 0.998) values close to 1, Mean Absolute Error (MAE = 1.42) and Mean Squared Error (RMSE = 1.79) values close to zero. These findings indicate that CEEMD demonstrated superior decomposition efficiency compared to the other six decomposition techniques. Additionally, the Kruskal-Wallis test conducted during the analysis phase yielded a statistical significance level of p > 0.05, confirming that the observed and predicted rainfall data originated from the same distribution. Consequently, the effectiveness and reliability of the proposed hybrid models for rainfall prediction were validated.
Citation - WoS: 12
Citation - Scopus: 14
Advanced Tunability of Optical Properties of CdS/ZnSe Multi-Shell Quantum Dot by the Band Edge Engineering
(Elsevier, 2023) Koc, Fatih; Kavruk, Ahmet Emre; Sahin, Mehmet
In this study, the advanced manipulability of wave functions in a type-II multi-shell hetero-nanostructure (MS-HNS) and the tunability of radiative exciton lifetime over a wide range with and/or without changing in transition energies has been demonstrated by the band edge engineering. For this purpose, the electronic and optical properties of exciton (X) and biexciton (XX) in a spherical CdS/ZnSe/ZnTe/CdSe HNS have been explored in detail. In the calculations, effects of all Coulombic interactions between the charges have been taken into account on the wave functions. Moreover, in the case of XX, the exchange-correlation potential between the same charged particles has also been considered. The results have been presented as a function of CdS core radius and ZnSe shell thickness and the probable physical reasons have been discussed in detail.
Citation - WoS: 35
Citation - Scopus: 39
Advances in Micelle-Based Drug Delivery: Cross-Linked Systems
(Bentham Science Publ Ltd, 2017) Isoglu, Ismail Alper; Ozsoy, Yildiz; Isoglu, Sevil Dincer
There are several barriers that drug molecules encounter in body beginning from kidney filtration and reticulo-endothelial system (RES) clearance to cellular trafficking. Multifunctional nanocarriers have a great potential for the delivery of drugs by enhancing therapeutic activity of existing methodologies. A variety of nanocarriers are constructed by different material types, which have unique physicochemical properties for drug delivery applications. Micelles formed by amphiphilic polymers are one of the most important drug/nanocarrier formulation products, in which the core part is suitable for encapsulation of hydrophobic agent whereas the outer shell can be utilized for targeting the drug to the disease area. Micelles as self-assembled nanostructures may encounter difficulties in biodistribution of encapsulated drugs because they have a tendency to be dissociated in dilution or high ionic strength. Therefore, therapeutic efficiency is decreased and it requires high amount of drug to be administered to achieve more efficient result. To overcome this problem, covalently stabilized structures produced by cross-linking in core or shell part, which can prevent the micelle dissociation and regulate drug release, have been proposed. These systems can be designed as responsive systems in which cross-links are degradable or hydrolysable under specific conditions such as low pH or reductive environment. These are enhancing characteristics in drug delivery because their cleavage allows the release of bioactive agent encapsulated in the carrier at a certain site or time. This review describes the chemical methodologies for the preparation of cross-linked micelles, and reports an update of latest studies in literature.
Advantage of Co-Culture Strategy for Targeted Cancer Treatment and in Vitro Studies
(Elsevier, 2021) Ulu, G. T.; Bayram, N. N.; Isoglu, S. Dincer; Baran, Y.
Akciğer Tümörlü Hastaların PET ve BT Görüntülerinin Çakıştırılıp Birleştirilmesi
(IEEE, 2015) Ayyildiz, Oguzhan; Yilmaz, Bulent; Karacavus, Seyhan; Kayaalti, Omer; Icer, Semra; Eset, Kubra; Kaya, Eser
Image fusion attracts attention in medical field due to complementary behavior and application such as diagnosis and treatment planning. In this study, first positron emission tomography (PET) and computed tomography (CT) images coming from 8 nonsmall cell lung cancer were registered then wavelet and principal component analysis methods were applied to fuse images. According to mutual information metric and nuclear medicine expert wavelet method gave better results when compared to PCA.
Citation - WoS: 3
Citation - Scopus: 3
Alantolactone Ameliorates Graft Versus Host Disease in Mice
(Elsevier, 2024) Odabas, Gul Pelin; Aslan, Kubra; Suna, Pinar Alisan; Kendirli, Perihan Kader; Erdem, Serife; Cakir, Mustafa; Unal, Ekrem
The anti-inflammatory and immunosuppressive drugs which are used in the treatment of Graft-versus-Host Disease (GVHD) have limited effects in controlling the severity of the disease. In this study, we aimed to investigate the prophylactic effect of Alantolactone (ALT) in a murine model of experimental GVHD. The study included 4 BALB/c groups as hosts: Naive (n = 7), Control GVHD (n = 16), ALT-GVHD (n = 16), and Syngeneic transplantation (n = 10). Busulfan (20 mg/kg/day) for 4 days followed by cyclophosphamide (100 mg/kg/day) were administered for conditioning. Allogeneic transplantation was performed with cells collected from mismatched female C57BL/6, and GVHD development was monitored by histological and flow cytometric assays. Additionally, liver biopsies were taken from GVHD patient volunteers between ages 2-18 (n = 4) and non-GVHD patients between ages 2-50 (n = 5) and cultured ex vivo with ALT, and the supernatants were used for ELISA. ALT significantly ameliorated histopathological scores of the GVHD and improved GVHD clinical scores. CD8+ T cells were shown to be reduced after ALT treatment. More importantly, ALT treatment skewed T cells to a more naive phenotype (CD62L+ CD44-). ALT did not alter Treg cell number or frequency. ALT treatment appears to suppress myeloid cell lineage (CD11c+). Consistent with reduced myeloid lineage, liver and small intestine levels of GM-CSF were reduced in ALT-treated mice. IL-6 gene expression was significantly reduced in the intestinal tissue. Ex vivo ALT-treated liver biopsy samples from GVHD patients showed a trend of decrease in proinflammatory cytokines but there was no statistical significance. Collectively, the data indicated that ALT may have immunomodulatory actions in a preclinical murine GVHD model.
Citation - WoS: 81
Citation - Scopus: 91
Alkali Activation of Mortars Containing Different Replacement Levels of Ground Granulated Blast Furnace Slag
(Elsevier Sci Ltd, 2012) Bilim, Cahit; Atis, Cengiz Duran
The aim of the present study is to investigate some properties of alkali-activated mortars containing slag at different replacement levels. Ground granulated blast furnace slag was used at 0%, 20%, 40%, 60%, 80% and 100% replacement by weight of cement, and liquid sodium silicate having three different Na dosages was chosen as the alkaline activator. In this research, carbonation resistance measurements and compressive and flexural strength tests were performed on the mortar specimens with size of 40 x 40 x 160 mm. The findings obtained from the tests showed that carbonation depth values of the mortars decreased with the increase of activator dosage. Additionally, compressive and flexural strength values increased with the increase in activator concentration and slag replacement level. Portland cement/slag mortars activated by liquid sodium silicate exhibited lower strength than the slag alone activated by the same activator. (C) 2011 Elsevier Ltd. All rights reserved.

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