Scopus İndeksli Yayınlar Koleksiyonu

Permanent URI for this collectionhttps://hdl.handle.net/20.500.12573/395

Browse

Now showing 1 - 20 of 1310

Citation - WoS: 1
Citation - Scopus: 1
Cinnamomum Zeylanicum Extract Incorporated Electrospun Poly(Lactic Acid)/ Gelatin Membrane as a New Wound Dressing
(Elsevier, 2025) Tarhan, Seray Zora; Pepe, Nihan Aktas; Sen, Alaattin; Isoglu, Ismail Alper
In this study, we fabricated poly(lactic acid)/gelatin electrospun membranes containing various concentrations of Cinnamomum zeylanicum extract and evaluated them as a novel wound dressing. The electrospun membranes were chemically, morphologically, and mechanically characterized, and the results were discussed in comparison with the literature. Electrospun membranes' biodegradability, swelling, and release properties were evaluated, with the CE7.5 membrane having values of 29.60 f 7.20 and 542.1 f 48.3 % and 66.9 %, respectively. Antibacterial activity was observed in CE7.5 and CE10 membranes against E. coli and S. aureus strains. At the highest concentration (CE10), 111.7 f 5.6 % and 96 f 12.375 % cell viability were detected in fibroblasts and differentiated LPS-induced THP-1 cells. Cell viability was further evaluated by Annexin-V/PI staining, revealing that 97.95 f 1.63 % of the cells remained viable in the CE7.5-treated membranes, while only 1.85 f 1.49 % of necrotic cells were detected in the treated cell population. Fibroblasts treated with the CE7.5 membrane showed a 42 % improvement in wound closure compared to non-treated cells. The anti-inflammatory properties of the electrospun membranes were also investigated. Treatment with the conditioned CE7.5 membrane downregulated Tba1 and tau proteins by 45.1 and 51.055 %, respectively. This study concluded that the newly developed Cinnamomum zeylanicum extract incorporated poly(lactic acid)/gelatin electrospun membranes could be a promising wound dressing material.
Citation - Scopus: 2
Future of Clean Cooking Energy Access in Emerging Economies by 2030
(Springer International Publishing, 2025) Çakır, Mehmet Ali; Ünlü, Ramazan; Çakir, Sümeyra Çay; Xanthopoulos, Petros
This study assesses the future of clean energy and technology access for cooking in emerging economic blocs—BRICS, MINT, ASEAN, and MENA—through 2030. Cooking contributes 3% of global greenhouse gas emissions, with over half of household emissions coming from cooking. Therefore, clean cooking energy is critical for sustainability and human health. The study aims to evaluate the likelihood of achieving the UN Sustainable Development Goal of universal clean cooking energy access by 2030 and the 2050 net-zero emissions target. Machine learning techniques, such as support vector regression, gradient boosting, and linear regression, alongside an ensemble approach, provide forecasts for these regions. The findings show a varied outlook. Within ASEAN, two countries are expected to reach 100% clean energy access for cooking by 2030, while two are likely to experience a decline. The MENA region shows stronger progress, with eight countries expected to meet the 2030 target. Among BRICS countries, only India is projected to reach full accessibility, while Russia faces a decline. The MINT countries face challenges, with none expected to meet the target, and Nigeria is projected to experience a decrease in clean energy access. The study concludes that the current trajectory makes achieving the 2030 Sustainable Development Goals and the 2050 net-zero emissions target unlikely for these regions. Policymakers must reassess their strategies and learn from successful countries to improve outcomes. © 2025 Elsevier B.V., All rights reserved.
Citation - WoS: 143
Citation - Scopus: 190
Extending the Technology Acceptance Model to Explain How Perceived Augmented Reality Affects Consumers' Perceptions
(Pergamon-Elsevier Science Ltd, 2022) Oyman, Mine; Bal, Dondu; Ozer, Serhat
Today, reaching consumers through interactive methods has become one of the primary goals of the brands. As a result of this, smartphones have turned into tools brands can use to start an interaction with consumers. Due to augmented reality (AR)-supported mobile applications, brands can both provide consumers with detailed information about products and services, and also affect consumers' perceptions. The main purpose of this research is to determine the effect of augmented reality use in mobile applications on consumers' behavioral intentions towards the use of the mobile application and perceptions underlying this effect. In this study, by employing the Technology Acceptance Model (TAM), the effect of augmented reality on behavioral intentions for mobile application use was examined through a structural equation modeling (SEM). Additionally, the effects of the technology anxiety (TA) and consumer novelty seeking (CNS) on perceived augmented reality were also examined. An augmented reality-supported mobile application which makes trying cosmetic products virtually on possible, was used by female consumers (n = 278). The data was collected through a questionnaire. The results indicated that the CNS had a positive and direct effect on perceived augmented reality (PAR); PAR had a positive and direct effect on perceived enjoyment (PE), perceived usefulness (PU), perceived informativeness (PI), and perceived ease of use (PEU). It was also determined that the PE, PU, PI had positive and direct effects on the behavioral intentions to use the application (BIUA).
Quasi-Static Operation of 2-Axis Microscanners With AlN Piezoelectric Quad-Actuators
(Institute of Electrical and Electronics Engineers Inc., 2021) Hah, D.
Aluminum nitride (AlN) started to draw attentions as a material for piezoelectric actuation owing to its CMOS process compatibility and safeness for biomedical applications. Due to its relatively low piezoelectric coefficients, AlN-based piezoelectric actuators have been mostly operated in resonance modes, especially in optical scanning. This paper presents a novel design of a 2-axis-tilt microscanner with AlN piezoelectric quad-actuators and meander-shaped hinges for reasonable quasi-static operation. Through finite-element-method simulation, it is shown that the proposed device can have about 9 degree of optical scan angle in two dimensions with the voltage amplitude of 50 V. Lissajous scanning operation of the device is demonstrated as well via simulation. © 2021 Elsevier B.V., All rights reserved.
Citation - Scopus: 19
A Novel Feature Design and Stacking Approach for Non-Technical Electricity Loss Detection
(Institute of Electrical and Electronics Engineers Inc., 2018) Aydin, Zafer; Güngör, Vehbi Çağrı
Non-technical electricity losses continue to jeopardize economic and social well-being of many countries. In this work, we develop machine learning classifiers that can identify anomalous electricity consumption in Turkey. Starting from weekly electricity usage data, we develop new features that capture statistical and frequency domain characteristics of the customers and their consumption patterns. We analyze the effect of reducing number of feature descriptors through dimensionality reduction and feature selection techniques. To overcome the class imbalance problem, we implement several ensemble methods and compare their prediction accuracy to those of the standard classifiers. The proposed features and combining strengths of different classifiers bring significant improvements on performance metrics, which is demonstrated through detailed simulations on shopping mall sector. We anticipate that advances in this field will contribute to the economies considerably. © 2018 Elsevier B.V., All rights reserved.
Citation - WoS: 22
Citation - Scopus: 27
Exploring Flood and Erosion Risk Indices for Optimal Solar PV Site Selection and Assessing the Influence of Topographic Resolution
(Pergamon-Elsevier Science Ltd, 2023) Yilmaz, Kutay; Dincer, Ali Ersin; Ayhan, Elif N.
This study explores the suitability of Mentes,e Region in Turkiye for the installation of solar PV farms, given the significant increase in energy demand in the country and the need to reduce reliance on fossil fuels. The Analytical Hierarchy Process (AHP) method, which has been widely used in previous studies, is employed to identify the most influential criteria for site selection, including environmental, economic, and social factors. However, this study introduces two new factors, flood hazard and erosion indices, to the analysis, which are crucial in areas susceptible to these hazards. The results show that approximately 7.5% of the study surface area is suitable for solar PV production. The study reveals that flood hazard and erosion indices have an effect on the suitable sites despite their relatively lower weights in the AHP. In addition, the study illustrates that site selection can be carried out using topographic data of lower resolution, as long as the data is resampled to match the resolution of land use data. The study is novel in its integration of flood and erosion risk indices in the decision process and its investigation of the influence of topographic resolution on site selection for solar PV panels.
Citation - WoS: 7
Citation - Scopus: 8
Parenting and Education: Navigating Class, Religiosity and Secularity in Istanbul
(Routledge Journals, Taylor & Francis Ltd, 2023) Kolluoglu, Biray; Dincer, Evren M.
This article studies the educational choices that secular and religious professional and managerial middle-class parents in Istanbul make for their children. It explores the ways in which class intersects with religion in Turkey where, politics, culture, social, and even economic life are marked by a deep divide among the religious and the secular. Focusing on a particular segment of the middle classes, that with higher economic and social capital, the article brings to fore the ways in which religiosity and secularity structure the processes of transforming privileges into acquired rights in the form of educational qualifications and extracurricular skills. It explores the current sociological conjuncture that bereaves both groups, albeit in different ways, of their ability to fully mobilize their accumulated economic, social, and cultural capitals in reproducing their class position in their children. The article argues that exploring the parenting of education along the secular and the religious divide can unravel the foundational elements of the ongoing competition and conflict in Turkey and enables a deeper understanding of the current divide and the potential for a future reconciliation. The study relies on a qualitative study that entails interviews with thirty families and two focus groups.
Citation - WoS: 8
Citation - Scopus: 11
A New Semi-Supervised Classification Method Based on Mixture Model Clustering for Classification of Multispectral Data
(Springer, 2018) Gogebakan, Maruf; Erol, Hamza
A new method for semi-supervised classification of remotely-sensed multispectral image data is developed in this study. It consists of unsupervised-clustering for data labelling and supervised-classification of clusters in multispectral image data (MID) using spectral signatures. Mixture model clustering, based on model selection, is proposed for finding the number and determining the structures of clusters in MID. The best mixture model, for the best clustering of data, finds the number and determines the structure of clusters in MID. The number of elements in the best mixture model fits to the number of clusters in MID. The elements of the best mixture model fits to the structure of clusters in MID. Clusters in MID is supervised-classified using spectral signatures. Euclidean distance is used as the discrimination function for the supervised-classification method. The values of Euclidean distances are used as decision rule for the supervised-classification method.
Phase-Synchronized Fluidic Oscillator Pair
(AMER INST AERONAUTICS ASTRONAUTICS, 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091-4344 USA, 2019) Tomac, Mehmet N; Gregory, James W.
The relative phase of oscillating jets from a pair of fluidic oscillators was synchronized in this work. The means for this synchronization was mutual interaction through a shared feedback channel between the two oscillators. Flow visualization and hot-wire measurements indicated a strong correlation and phase synchronization between the two oscillators. A numerical analysis offered better understanding of the internal flow physics that led to the synchronization phenomenon. A portion of the output jet from one fluidic oscillator was redirected and crossed over into the adjacent oscillator, leading to momentum transfer between the two oscillators. A portion of this cross-oscillator flow was directed into the shared feedback channel and constituted the main feedback flow. In this process, one of the shared feedback channel outlets was blocked by a vortex, allowing only one oscillator to receive feedback flow. The primary mechanism for in-phase synchronization was the cross-oscillator flow, which was divided into phase-modulated momentum injection to the primary jet and modulated flow input to the shared channel feedback channel.
Citation - WoS: 28
Citation - Scopus: 30
A New Parameter Influencing the Reaction Kinetics and Properties of Fly Ash Based Geopolymers: A Pre-Rest Period Before Heat Curing
(Elsevier, 2021) Durak, Ugur; Ilkentapar, Serhan; Karahan, Okan; Uzal, Burak; Atis, Cengiz Duran
In this study, the influence of a pre-rest period before heat curing (as a new parameter), on the physical properties, flexural and compressive strength, and microstructure of geopolymer mortars and pastes produced with alkali activation of fly ash were investigated. In this context, geopolymer mortar and paste samples were prepared and pre-rested under laboratory conditions for 0, 1, 2, 3, 7, 14, and 28 days before heat curing. After the pre-rest period, the samples were subjected to heat curing at 75 degrees C in an oven, for 2 days. Mortar and paste samples exposed to a pre-rest period while in the fresh state before heat curing were compared with control samples without pre-resting. Water absorption, porosity, specific gravity, capillarity, flexural strength, compressive strength, and abrasion resistance tests were conducted on the geopolymer mortar samples. A reaction kinetics study using an isothermal calorimeter, XRD, and SEM analyses were performed on the geopolymer paste samples for microstructural investigations. Based on the results obtained, it was observed that the mechanical strength of the samples subjected to the pre-rest period before heat curing increased considerably compared to the reference (without pre-resting) samples. In addition, because of pre-resting, the capillarity coefficient, water permeability, and porosity of the samples decreased compared to the reference samples, and it was concluded that pre-resting improves durability-related properties. Moreover, the reaction kinetics and SEM analysis results, supporting the above findings, showed that a pre-resting period increases the geopolymeric reaction products and causes a denser microstructure.
Citation - WoS: 16
Citation - Scopus: 16
Hexagonal Nanosheets in Amorphous BN: A First Principles Study
(Elsevier Science Bv, 2015) Durandurdu, Murat
Amorphous boron nitrite is modeled by means of first principles molecular dynamics simulations and found to be almost chemically ordered in a stark contrast to the previous predictions. Its average coordination number is 2.97. The main building unit of the amorphous network is hexagonal rings as in the most stable boron nitrite phase but chain-like structures and tetragonal-like rings also exist in amorphous network. The model consists of partially hexagonal nanosheets and hence it is not entirely disordered. Amorphous boron nitrite has a band gap energy of about 2.0 eV. (C) 2015 Elsevier B.V. All rights reserved.
Citation - WoS: 29
Citation - Scopus: 41
Optimisation of the Reaction Conditions for the Production of Cross-Linked Starch With High Resistant Starch Content
(Elsevier Sci Ltd, 2015) Kahraman, Kevser; Koksel, Hamit; Ng, Perry K. W.
The optimum reaction conditions (temperature and pH) for the preparation of cross-linked (CL) corn and wheat starches with maximum resistant starch (RS) content were investigated by using response surface methodology (RSM). According to the preliminary results, five levels were selected for reaction temperature (38-70 degrees C) and pH (10-12) in the main study. RS contents of the CL corn and wheat starch samples increased with increasing temperature and pH, and pH had a greater influence on RS content than had temperature. The maximum RS content (with a maximum p value of 0.4%) was obtained in wheat starch cross-linked at 38 degrees C and pH 12. In the case of CL corn starch, the optimum condition was 70 degrees C and pH 12. CL corn and wheat starch samples were also produced separately under the optimum conditions and their RS contents were 80.4% and 83.9%, respectively. These results were also in agreement with the values predicted by RSM. (C) 2014 Elsevier Ltd. All rights reserved.
Broadband Low Reflection Surfaces With Silicon Nanopillar Hexagonal Arrays for Energy Harvesting in Photovoltaics
(Springer, 2022) Tut, Turgut
In this study, optimization of the silicon nanopillar arrays and thin films coated on silicon substrate has been investigated in order to minimize the optical reflection loss from the silicon substrate surface. Nanopillars's filling ratio, pillar height, pillars diameter, sidewall incline angle, and step coverage with dielectric thin film thickness are systematically optimized together for the first time with these type of nanostructures. Full-field Finite Difference Time Domain method is used to simulate electro-magnetic fields and calculate the reflection from the modified nanostructured substrate surfaces in 400-1100 nm spectral range. Optimization recipe is clearly presented and this is not only useful for hexagonal arrays but also for regular arrays of nanopillars in general. We also further decrease the reflection by using step coverage concept which is the result of nonconformal coating on steps and trenches of thin films. We obtained approximately 2% of weighted average reflection in the 400-1100 nm range for perpendicular incident solar radiation which is one of the best results reported for this type of nanostructured surfaces in the literature.
Citation - WoS: 18
Citation - Scopus: 21
Synthesis of L-Cysteine Capped Silver Nanoparticles in Acidic Media at Room Temperature and Detailed Characterization
(Springer, 2018) Panhwar, Sallahuddin; Hassan, Syeda Sara; Mahar, Rasool Bux; Canlier, Ali; Sirajuddin; Arain, Munazza
This work reports a simple and one pot synthesis of water dispersible l-cysteine stabilized silver nanoparticles (l-CYS-AgNPs) in an acidic media. Silver nanoparticles were synthesized within few minutes of reaction time (< 5 min) at room temperature without needing to heat and use of any hazardous organic solvents. Prepared nanoparticles were characterized by UV-Visible spectroscopy, Fourier transform infrared spectroscopy, transmission electron microscopy, atomic force microscopy, X-ray diffraction and zeta potential analysis, respectively. Surface plasmon resonance band of AgNPs which was observed at 392 nm by UV-Visible spectroscopy indicated successful formation of l-CYS-AgNPs in acidic media. Imaging techniques showed that AgNPs possess spherical morphology and average size of 25 nm. Nanoparticles were stable for more than 2 months when stored at ambient temperature. This approach is a facile and rapid one pot synthesis which can be stored as a homogenous aqueous dispersion for more than 2 months. Being stabilized by a sulfur-containing amino acid (l-cysteine) and the synthesis carried out in a moderately acidic media (pH 5.3) are distinctive aspect of this work. These stable l-CYS-AgNPs could be used as a catalyst and sensor applications for advanced perspective against water pollution and industrial effluents.
Citation - Scopus: 3
Solving Optimization Problem With Particle Swarm Optimization: Solving Hybrid Flow Shop Scheduling Problem With Particle Swarm Optimization Algorithm
(Springer, 2021) Madenoğlu, Fatma Selen
The flow shop scheduling problem is widely discussed in the literature since it is frequently applied in real industry. This paper presents a variant of flow shop scheduling problem with parallel machines. The proposed problem includes multistage and identical parallel machines at each stage, and the sequence-dependent setup time and transportation time are considered. The objective function is minimization of makespan. The particle swarm optimization algorithm (PSO) is addressed to solve the problem and compared with genetic algorithm and heuristics. The benchmark instances are generated to demonstrate the performance of the PSO. The numerical results show that the PSO significantly outperforms the comparison set. © 2021 Elsevier B.V., All rights reserved.
Citation - Scopus: 5
Emotion Detection Using Multivariate Synchrosqueezing Transform via 2D Circumplex Model
(Institute of Electrical and Electronics Engineers Inc., 2018) Ozel, Pinar; Akan, Aydin; Yilmaz, Bulent; Özel, Pınar; Akan, Aydin I.; Yilmaz, Bulent
Emotion detection by utilizing signal processing methods is a challenging area. An open issue in emotional modeling is to obtain an optimum feature set to use for the classification process. This study proposes an approach for emotional state classification by the investigation of EEG signals via multivariate synchrosqueezing transform (MSST). MSST is a post-processing technique to compose a localized time-frequency representation yielding multivariate syncyrosqueezing coefficients. After obtaining these coefficients from EEG signals for 18 subjects from DEAP dataset, coefficients and self-assessment-mannequins (SAM) labels of those subjects are used for emotional state classification by using support vector machines (SVM) nearest neighbor, decision tree, and ensemble methods. The accuracy rate is 70.6% for high valence high arousal (HVHA), 75.4% for low valence high arousal (LVHA), 77.8% for high valence low arousal (HVLA), and 77.2% for low valence low arousal (LVLA) cases using SVM. © 2019 Elsevier B.V., All rights reserved.
Citation - WoS: 26
Citation - Scopus: 29
A Detailed Investigation of Electronic and Optical Properties of the Exciton, the Biexciton and Charged Excitons in a Multi-Shell Quantum Dot Nanocrystal
(IOP Publishing Ltd, 2014) Akturk, Abdurrahman; Sahin, Mehmet; Koc, Fatih; Erdinc, Ahmet
In the present study, the electronic and optical properties of the exciton (X), the biexciton (XX) and charged excitons (X- and X+) in a multi-shell quantum dot nanocrystal have been systematically explored in detail. The electronic properties have been determined in the framework of the single-band effective mass approximation. For this purpose, the Poisson-Schrodinger equations have been solved self-consistently in the Hartree approximation. In the electronic structure calculations for XX, X- and X+, the quantum mechanical exchange-correlation potentials between particles of the same type have been taken into account in the local density approximation. Some optical parameters, such as the overlap integrals, recombination oscillator strengths, radiative lifetimes, etc, have been determined by using the single-particle energy levels and wavefunctions obtained. A different approximation, reported in Sahin and Koc 2013 Appl. Phys. Lett. 102 183103, has been used in the recombination oscillator strength calculations. The results have been presented comparatively as a function of the shell thicknesses, and the well widths and probable physical reasons underlying them have been discussed in detail.
Citation - Scopus: 1
Detection of Epileptic Seizures With Tangent Space Mapping Features of EEG Signals
(IEEE, 2021) Altindis, Fatih; Yilmaz, Bulent
Detection of epileptic seizures from EEG signals is well-studied topic for the last couple of decades. Lately, automated signal processing and machine learning methods were developed to detect epileptic seizures. However, most of the methods are tailored to subjects and require fine tuning of many parameters. In this study, we proposed to use Riemannian geometry-based signal processing method that already showed superior performance on brain-computer interface problems, to extract features. We showed that tangent space mapping features of EEG signals can be used to detect seizures with high accuracy and precision.
Citation - Scopus: 7
A Comparative Analysis on Medical Article Classification Using Text Mining & Machine Learning Algorithms
(Institute of Electrical and Electronics Engineers Inc., 2021) Kolukisa, Burak; Dedeturk, Bilge Kagan; Dedeturk, Beyhan Adanur; Gulsen, Abdulkadir; Bakal, Gokhan
The document classification task is one of the widely studied research fields on multiple domains. The core motivation of the classification task is that the manual classification efforts are impractical due to the exponentially growing document volumes. Thus, we densely need to exploit automated computational approaches, such as machine learning models along with data & text mining techniques. In this study, we concentrated on the classification of medical articles specifically on common cancer types, due to the significance of the field and the decent number of available documents of interest. We deliberately targeted MEDLINE articles about common cancer types because most cancer types share a similar literature composition. Therefore, this situation makes the classification effort relatively more complicated. To this end, we built multiple machine learning models, including both traditional and deep learning architectures. We achieved the best performance (R¿82% F score) by the LSTM model. Overall, our results demonstrate a strong effect of exploiting both text mining and machine learning methods to distinguish medical articles on common cancer types. © 2022 Elsevier B.V., All rights reserved.
Citation - WoS: 8
Citation - Scopus: 8
Involvement of Sphingolipid Metabolism Enzymes in Resveratrol-Mediated Cytotoxicity in Philadelphia-Positive Acute Lymphoblastic Leukemia
(Routledge Journals, Taylor & Francis Ltd, 2022) Oguz, Osman; Adan, Aysun
Targeting the key enzymes of sphingolipid metabolism including serine palmitoyltransferase (SPT), sphingosine kinase (SK) and glucosylceramide synthase (GCS) has a therapeutic importance. However, sphingolipid metabolism-mediated anti-leukemic actions of resveratrol in Philadelphia-positive acute lymphoblastic leukemia (Ph + ALL) remain unknown. Therefore, we explored potential mechanisms behind resveratrol-mediated cytotoxicity in SD1 and SUP-B15 Ph + ALL cells in the context of sphingolipid metabolism and apoptosis induction. The anti-proliferative and apoptotic effects of resveratrol alone and in combination with SPT inhibitor (myriocin), SK inhibitor (SKI II), GCS inhibitor (PDMP) were determined by MTT cell proliferation assay and flow cytometry, respectively. The effects of resveratrol on PARP cleavage, SPT, SK and GCS protein levels were investigated by Western blot. Resveratrol inhibited proliferation and triggered apoptosis via PARP activation and externalization of phosphatidylserine (PS). Resveratrol increased the expression of SPT whereas it downregulated SK and GCS. Resveratrol's combinations with SKI II and PDMP intensified its anti-leukemic activity by increasing the relocalization of PS while its combination with myriocin suppressed apoptosis. Therefore, resveratrol inhibited cell proliferation and induced apoptosis through modulating SK, GCS and SPT expression, which may be considered as novel biomarkers of resveratrol-induced cytotoxicity in Ph + ALL.

Browse

Browsing Scopus İndeksli Yayınlar Koleksiyonu by Access Right "info:eu-repo/semantics/closedAccess"