Sürdürülebilir Kalkınma Amaçları
Yazarlar
- Kamiloğlu, Aybike(6)
- Kutlu, Naciye(6)
- Ecem Bayram, Nesrin(5)
- Bayram, Ozkan(4)
- Bayram, Sinan(4)
- Igman, Erdal(4)
- Teber, Ahmet(4)
- Tutkun, Cansu(4)
- Dertli, Enes(3)
- Elbir Abca, Tuğba(3)
- Gerçek, Yusuf Can(3)
- Guleryuz, Didem(3)
- Simsek, Onder(3)
- Çolak, Murat(3)
- İspirli, Hümeyra(3)
- Abdioglu, Murat(2)
- Ari-Arat, Ceren(2)
- Can, Zehra(2)
- Ekincioğlu, Yavuz(2)
- Eryılmaz Türkkan, Gökçen(2)
- Güven, Ebru Mazlum(2)
- Güven, Onurhan(2)
- Hasar, Ugur Cem(2)
- Hırca, Tuğçe(2)
- Kara, Yakup(2)
- Kolaylı, Sevgi(2)
- Kotaman, Hüseyin(2)
- Kızıl, Hamit Emre(2)
- Niazkar, Majid(2)
- Sarac, Mehmet Fahri(2)
- Sayan, Enes(2)
- Yaman, Havva(2)
- Yetişensoy, Okan(2)
- Yılmaz, Özlem(2)
- Çakiroğlu, Ünal(2)
- Abdolahpour Salari, Maryam(1)
- Adiyaman, Gokhan(1)
- Afzali, Seied Hosein(1)
- Akaras, Nurhan(1)
- Akgun, Nurullah(1)
Yayınlar
- MakaleAçık Erişim2025Scopus SJRQ3Tailoring the optoelectronic properties of ZnO nanowires via TiO2 coating
Sarac, Mehmet Fahri; Mert, Merve; Solakyildirim, Tuba; Teber, Ahmet
The photosensing properties of TiO2/ZnO nanowires (NWs) were investigated by sequential deposition using thermal oxidation and sol–gel. It was found that TiO2/ZnO NWs with 5 mM concentration exhibit a higher aspect ratio compared to the 10 mM and 25 mM TiO2/ZnO NWs. The surface-to-volume ratio directly influences the photoluminescence (PL) intensity and electrical properties of the ZnO NWs. XPS confirmed the presence of TiO2 on the surface, while EDS detected titanium, with its concentration increasing as the TiO2 concentration rises. The photosensing performance of ZnO has been significantly improved by modifying it with TiO2. However, determining the optimum concentration is a critical factor in performance improvement. The findings show that high TiO2 concentrations improve surface properties, but excessive coating may limit carrier mobility. Photosensitivity has been increased at lower TiO2 concentration due to a higher surface-to-volume ratio (SVR) and, as a result, higher surface photoactivity. The 25 mM TiO2/ZnO NW array stands out in optimal detectability and photoresponsivity due to the reduced resistance caused by the increased Ti concentration on the surface. The 25 mM TiO2/ZnO NWs achieved the highest photoresponsivity (717 mA/W) and specific detectivity (1.48 × 101° Jones), while the 5 mM TiO2/ZnO NWs exhibited exceptional photosensitivity (320.11%), making them ideal for UV detection. The samples at varying concentrations show promise in photosensitivity, detectability, and photoresponsivity, making them suitable for environmental sensors, UV detectors, and other optoelectronic applications.
AtıfOpenAlex1
İncele - MakaleYalnız künye2025Scopus SJRQ1A psychometric analysis of the artificial intelligence skills scale developed through chat gpt
Görgülü, Deniz; Coşkun, Fatma; Demi̇r, Mustafa; Si̇pahi̇oğlu, Mete
This study aims to examine the psychometric properties of a scale developed to measure teachers’ ability to use artificial intelligence tools in education. The scale was originally proposed as having 33 items across 5 sub-dimensions by Chat GPT-4, an AI system. To establish content validity, the scale form was submitted to expert review. An exploratory factor analysis (EFA) was then conducted on a sample of 347 teachers to determine if the 33-item, 5-subdimensional structure proposed by Chat GPT was confirmed by empirical data. The EFA results supported Chat GPT-4’s proposed structure. A confirmatory factor analysis (CFA) was applied to a new sample of 603 teachers to assess the scale’s validity in an independent sample. The CFA results did not fully support the structure consisting of 33 items and 5 subdimensions proposed by Chat GPT. Reliability was analyzed using Cronbach’s Alpha and test-retest methods.
AtıfScopus5WoS5OpenAlex10İncele - MakaleAçık Erişim2025Scopus SJRQ1Electrospinning Encapsulation of Chlorophylls Microwave-Extracted from Spinach Waste and Utilization as Coloring Agent in Yogurt
Isik, Beyza Sukran; Bayram, Sinan; Altay, Filiz
Natural colorants have become a developing market because of consumer preferences, and more cost-effective and stable production is necessary. In the present study, a natural green colorant was obtained via microwave-assisted extraction from spinach waste to produce affordable, environmentally-friendly, and innovative colorants. The extracts were encapsulated with zein via uniaxial and coaxial electrospinning techniques to overcome the stability issues associated with their natural green color. The encapsulation efficiencies of uniaxially encapsulated chlorophyll extracted from spinach waste by microwave were 63.50 and 57.18 for chlorophyll a and b, respectively. The efficiencies of chlorophyll a and b by coaxial electrospinning were found 49.53% and 88.58%, respectively. The microwave-assisted extraction and the addition of eumelanin may contribute positively to the antioxidant activity and thermal stability of electrospun samples. The stability test against light revealed that 61% of chlorophyll a could be preserved by uniaxial electrospinning. In addition, when chlorophyll-loaded nanofibers were incorporated into yogurt, a more stable green color was achieved during storage.
AtıfScopus10WoS9OpenAlex11İncele - MakaleAçık Erişim2024Scopus SJRQ2Free Vibration and Buckling Analysis of Porous Two-Directional Functionally Graded Beams Using a Higher-Order Finite Element Model
Turan, Muhittin; Adiyaman, Gokhan
A new type of functionally graded material (FGM) with material properties varying in two or three directions is needed to obtain materials with better mechanical properties and high-temperature resistance for use in the military, aerospace, automotive, and engineering structures. Considering the porosity that occurs during the production of these materials, it has become necessary to examine the free vibration and buckling behaviors. Therefore, this study investigated free vibration and buckling analysis of porous two-directional functionally graded (2D FG) beams subject to various boundary conditions. A high-order finite element based on parabolic shear deformation theory (PSDT) is proposed to solve this problem. Three types of porosity distributions were used in the study (FGP-1, FGP-2, and FGP-3). The governing equations are derived from Lagrange’s principle. The material change in the beam volume in both directions is defined by a power-law rule. The dimensionless fundamental frequencies and critical buckling loads are obtained for various boundary conditions, gradation exponents (px, pz), porosity coefficient (e), porosity distribution, and slenderness (L/h). The numerical results obtained with the proposed higher-order finite element are compatible with the literature.
AtıfScopus47WoS44OpenAlex40İncele - MakaleAçık Erişim2024Scopus SJRQ1The effect of AI-powered chatbots in social studies education
Yeti̇şensoy, Okan; Karaduman, Hıdır
The aim of this research is to investigate the educational potential of AI-powered chatbots in Social Studies learning-teaching processes. The study was conducted using embedded design, evaluated within the framework of mixed methods research. The study group consists of 78 6th-grade students studying in three different classes, along with one teacher who implemented the practices and guided the process. During the experimental phase of the study, lessons in the experimental group were taught by the practitioner teacher using an AI-powered chatbot named “SosyalciBot”. Meanwhile, lessons in two control groups were taught following the constructivist approach. At the end of the process, it was determined that the experimental group students’ post-test and permanency test scores were significantly higher than the control group students’ scores in both post-test and permanency test. In the semi-structured interviews, both students and the practitioner teacher provided positive evaluations of the pedagogical and design features of the chatbot, indicating that these features positively impacted the learning-teaching process. They also identified some shortcomings while offering suggestions for improvement. Based on the study findings, it is evident that chatbots have a high potential to contribute to Social Studies education. However, to fully harness this potential and achieve optimal effectiveness, further advancements and refinements in chatbot technology are required. At this point, it is recommended to conduct theoretical or applied studies focusing on developing chatbots with high communication capacity and explore innovative and constructive ideas regarding the integration of chatbots into educational environments.
AtıfScopus58WoS37İncele - MakaleYalnız künye2024Scopus SJRQ3Comparison of Superconducting Properties of Bulk MgB2 Samples with Pyrene Additive Produced by B Powder and C encapsulated B Powder
Erdem, Özge
In this paper, the advantages and disadvantages of using B powder and C encapsulated B powder as a precursor during the production process of MgB2 with the addition of pyrene (C16H10) were investigated. Two MgB2 bulk samples with the addition of 10 wt % C16H10 of 1 g MgB2 were produced by the in-situ method using B powder and C encapsulated B powder. The C encapsulated B powder as a precursor was prepared by adding 10% C16H10 as a C source. From XRD and SEM analysis, a greater increase in MgO phase and a greater decrease in a-lattice parameter were observed for the sample produced with B, compared to the sample produced with C encapsulated B. The curves of critical current density (Jc) at 5 K showed a similar character for both samples. The Jc values at 5 K in self field were respectively obtained as 1.52 × 105 A/cm2 and 1.90 × 105 A/cm2 for the samples produced by B and C encapsulated B. The decrement ratio of in-field Jc at 20 K was less affected by increasing magnetic field for the sample produced using C encapsulated B due to the relatively higher increase in the irreversibility field (Hirr) and the upper critical magnetic field (Hc2) values. The Jc values at 20 K and 3 T were respectively determined as 1.49 × 104 A/cm2 and 1.93 × 104 A/cm2 for the samples produced with B and C encapsulated B.
AtıfScopus2WoS2OpenAlex2İncele - MakaleAçık Erişim2024Scopus SJRQ2Investigation of Mass Transfer of Ozone in Jet Loop Reactor
Cengiz, Ibrahim; Değermenci, Nejdet; Yildiz, Ergun; Barlak, Melahat Semin
Mass transfer of ozone in a jet loop reactor was investigated in this study. Different parameters such as ozone gas concentration, gas flow rate, circulation flow rate, and spray nozzle diameter were examined for their effect on mass transfer. In experiments with ozone gas concentrations ranging from 3.83 to 17.1 g/m3, the KLa values remained unchanged, with an average of 28.7 ± 2.2 h−1. As the ozone gas concentration increased, the saturation values of ozone in the liquid phase also increased. Experiments were carried out with gas flow rates ranging from 50 to 250 L/h in the jet loop reactor, and increasing gas flow rates increased the KLa value up to five times. When the effect of the liquid circulation flow rate was examined for a spray nozzle diameter of 15.5 mm, increasing the flow rate from 40 L/min to 80 L/min increased the KLa value by approximately 41%. However, the power consumed per reactor volume for this process increased 8 times and reached 2.65 kW/m3. KLa values in the JLR vary between 6.1 and 37.3 h−1 depending on operating parameters and it has been concluded that it performs well compared to its counterparts.
AtıfScopus6WoS6OpenAlex7İncele - MakaleAçık Erişim2024Scopus SJRQ3Durability of slag-based alkali-activated materials: A critical review
Gökçe, H.S.
As the world becomes increasingly aware of the devastating effects of climate change, the need for sustainable building materials that are both durable and environmentally friendly increases. Geopolymer and alkali-activated materials formed by a chemical reaction between an alkaline activator solution and an aluminosilicate source have gained popularity in recent years. The alkaline activator solution dissolves the aluminosilicate source, which then undergoes a polycondensation reaction to form a three-dimensional geopolymeric gel network. The development of this network ensures the strength and durability of the material. Today, this phenomenon of durability has been studied in detail to enable the development of superior construction materials, taking into account degradation mechanisms such as carbonation, leaching, shrinkage, fire, freezing and thawing, and exposure to aggressive environments (chlorides, acids, and sulphates). Although there are many unsolved problems in their engineering applications, slag-based alkali-activated materials appear to be more advantageous and are promising as alternative materials to ordinary Portland cement. First of all, it should not be ignored that the cure sensitivity is high in these systems due to compressive strength losses of up to 69%. Loss of strength of alkali-activated materials is considered an important indicator of degradation. In binary precursors, the presence of fly ash in slag can result in an improvement of over 10% in compressive strength of the binary-based alkali-activated materials after undergoing carbonation. The binary systems can provide superior resistance to many degradation mechanisms, especially exposure to high-temperature. The partial presence of class F fly ash in the slag-based precursor can overcome the poor ability of alkali-activated materials to withstand high temperatures. Due to the desired pore structure, alkali-activated materials may not be damaged even after 300 freeze–thaw cycles. Their superior permeability compared to cementitious counterparts can extend service life against chloride corrosion by more than 20 times. While traditional (ordinary Portland cement-based) concrete remains the most widely used material in construction, geopolymer concrete’s superior performance makes it an increasingly emerging option for sustainable and long-lasting infrastructure.
AtıfScopus69WoS63OpenAlex70İncele - MakaleAçık Erişim2024Scopus SJRQ1Analytical approach to contact mechanics of functionally graded orthotropic layers with gravitational considerations
Öner, Erdal; Al-Qado, Ahmed Wasfi Hasan
Contact problems involving deformable bodies are widespread in both industrial and everyday situations. They have a crucial impact on structural and mechanical systems, which has led to significant efforts in modeling and numerical simulations. These efforts aim to improve understanding and optimization in various engineering applications. This study examines the contact problem involving a functionally graded (FG) orthotropic layer resting on a rigid foundation, without considering frictional influences. A point load is applied to the layer through a rigid punch on its top surface. Additionally, the gravitational effects of the FG orthotropic layer are considered in the analyses. Material parameters and density of the FG orthotropic layer are presumed to exhibit exponential variations along the vertical axis. The resolution of the problem involves deriving stress and displacement expressions through the application of elasticity theory and integral transformation techniques. By imposing the pertinent boundary conditions onto these expressions, a singular integral equation is formulated, wherein the contact stress under the punch remains unknown. Employing the Gauss–Chebyshev integration method, this integral equation is subsequently numerically solved, particularly for a flat punch profile. The outcomes of this investigation encompass the determination of contact stresses under the punch, the critical separation load, and the critical separation point—marking the initial separation between the FG orthotropic layer and the rigid foundation. Additionally, the analysis yields dimensionless representations of normal stresses along the symmetry axis within the FG orthotropic layer, as well as shear stresses along a designated section proximate to the symmetry axis. Furthermore, it provides insights into the normal stresses along the x axis at the bottom surface of the FG orthotropic layer, contingent upon various parameters and distinct orthotropic material compositions.
AtıfScopus12WoS12OpenAlex12İncele - MakaleAçık Erişim2024Scopus SJRQ2A Dual-Band Terahertz Metamaterial Absorber Using an All-Metal Aluminum Hexagonal Metasurface Structure for Sensing of Cancerous Cells
Teber, Ahmet
This article proposes a dual-band terahertz metamaterial absorber (TMA) where all components of the designed structure are made of aluminum (optical) material. Unlike the metal-dielectric-metal structures typically found in the literature, the proposed structure has a lightweight material that does not contain a sandwich structure. Thus, the structure greatly simplifies the production process and reduces the cost. The results of electromagnetic and equivalent circuit simulations are compared based on the S11 parameters (in dB), resulting in good agreement of findings by CST and ADS, respectively. The proposed TMA operates in dual frequency bands at 1.902 THz (f1) and 1.976 THz (f2), with strong absorption of 98.17% and 99.05%, respectively. The quality factors (Q-factors) corresponding to these resonant frequencies are 240.15, (f1) and 181.61, (f2). When the refractive index (RI) of the medium surrounding the TMA varies, the absorption peaks shift accordingly. The detection properties of the proposed TMA are examined as the RI of the surrounding medium is varied primarily between 1.34 and 1.39 with an increase of 0.01 for biomedical applications. The corresponding sensitivities of two resonance peaks are 0.794 THz/RIU and 0.971 THz/RIU, respectively. Since many samples, such as human blood, basal/breast/cervical cells, and cancerous cells, are found in this RI range, the proposed TMA sensor can be used as a viable biosensor in the identification of biological samples for real-world applications. Graphical Abstract: (Figure presented.)
AtıfScopus36WoS31OpenAlex37İncele - Kitap BölümüYalnız künye2024Microwave Roasting
Kutlu, Naciye; Pandiselvam, Ravi
Roasting is a process that involves heat treatment to improve the digestibility, flavor and sensory aspects of foods and to provide the desired structural changes in the food product. In the microwave roasting method, the heat treatment applied to food products uses microwave energy. When this method is applied with the right temperature-time combination, it has many advantages, such as shorter processing time, energy efficiency, preserving the color components and nutritional quality to a large extent, prevention of the formation of acrylamide to a large extent and offering easy process control compared to traditional methods (roasting in pan, sand or oven), and therefore it has come to the fore in recent studies. With appropriate optimization studies, the negative effects of the microwave method will be minimized. Studies are needed to adapt the microwave roasting method on an industrial scale. Designing new devices which can use artificial intelligence for microwave roasting, an innovative and economical method, is among research expectations for the future.
AtıfScopus1İncele - MakaleAçık Erişim2024Scopus SJRQ2Niobium modification on dielectric, magnetic and structural features of nanocrystalline Ni–Co ferrites
Teber, Ahmet; Sarac, Mehmet Fahri
In this study, we will investigate the structural, characteristic, dielectric and magnetic features of Co0.5Ni0.5Nb xFe2–xO4 (0.0 ≤ x (with 0.2 increments) ≤ 1.0) nanoparticles, which are prepared via the hydrothermal approach. M-type hexagonal crystal structures are confirmed through XRD, FT-IR, SEM-EDS, TEM-SAED and VSM. Also, we have reported the investigations on dielectric properties and ac conductivity. Based on XRD measurements, it is concluded that all samples have M-type hexagonal crystal structure with nanocrystals ranging from 60 to 97 nm. The diffraction patterns obtained matched well with the calculated patterns from Rietveld analysis. Moreover, from the morphological analysis, it was observed that the small spherical structures of Ni–Co ferrite particles transformed into quadrilateral structures with increasing Nb concentration. The results of the FT-IR study show that the hexaferrite structure is formed as predicted because the expected range of absorption bands is present. According to VSM, Nb-substituted Ni–Co ferrite nanostructures reveal a relatively soft ferromagnetic property. Increasing the concentration of Nb tends to increase the coercive field (H c) variation. The dielectric factors and ac conductivity were measured in the frequency range of 0.1–10 MHz. The reduction in dielectric factors and tangent losses at low frequencies can be elucidated by both deformation and relaxation polarization mechanisms. Another observation is that ac conductivity is amplified with the applied frequency. In this sense, the electron and hole hopping phenomenon can explain the conduction mechanism.
- MakaleAçık Erişim2024Scopus SJRQ2Optimization of pectin extraction from crab apple peel and usage in a model meat emulsion system
Aldemir, Hazal; Kamiloğlu, Aybike; Çakır, Özlem
The aim of this study was to optimize conditions of microwave-assisted pectin extraction from crab apple peels using the Box–Behnken experimental design. For this purpose, microwave-assisted pectin extraction was performed at different extraction time (3, 6, and 9 min), liquid/solid ratio (75, 100, and 125), and pH (1.5, 2.0, 2.5). The optimum conditions were selected as extraction time (7.77 min), liquid/solid ratio (77.53 mL/g), and pH/1.79). The response, obtained under optimum conditions was determined as 0.1128 ± 0.0137 g pectin/g crab apple peel. In addition, it was determined that the obtained pectin sample had an esterification degree of 79.14% and oil and water binding capacities of 8.5 ± 0.7 g oil/g pectin and 8.1 ± 1.5 g water/g pectin, respectively. It was determined that pectin emulsions showed higher stability at 1% pectin level. The possibilities of using pectin obtained under optimized conditions as a fat replacer in a model sausage system were investigated. Pectin was evaluated in the model sausage system at two different concentrations. With the increasing pectin concentration, the cooking loss value increased from 14 to 18%, while leakage decreased from 0.31% to 0.18%, showing a negative effect on cooking loss and a positive impact on the amount of leakage into the packaging. Pectin obtained from crab apple peel has the potential to be used for reducing fat content in sausage environment.
AtıfScopus15WoS12OpenAlex14İncele - MakaleAçık Erişim2024Scopus SJRQ3Investigation of Hot Press and Cold Press Effects on Structural, Electrical and Magnetic Properties of Pyrene Added Bulk MgB2
Erdem, O.
In this paper, the effects of hot pressing and cold pressing on the superconducting properties of pyrene (C16H10) added bulk MgB2 were compared. For this aim, the polycrystalline disk-shaped MgB2 samples with addition of 4 wt % C16H10 powder were fabricated by a pellet/closed tube method at 850 °C, after hot pressing at 200 °C and cold pressing. The XRD and SEM results showed that although a-lattice parameters reduce for both C16H10 added samples, the average crystallite size increases after cold pressing because of the accumulation and inhomogeneous distribution of C in the MgB2 structure while it reduces for the C16H10 added hot pressed sample. The resistivity measurements showed that the increment of electron scattering is higher for the C16H10 added cold pressed sample than that of the C16H10 added hot pressed one which shows relatively better grain connectivity, and the Tc values of the samples are not appreciably affected by the pressing conditions. From the magnetisation measurements the in-field Jc values at 10 K and 5.5 T were obtained as 8.41 × 103 A/cm2, 1.62 × 104 A/cm2, 6.90 × 103 A/cm2 and the Hirr values while Jc = 100 A/cm2 at 20 K were obtained as 5.99 T, 6.55 T and 6.19 T for the pure sample and the C16H10 added hot and cold pressed samples, respectively. The higher Jc and Hirr values obtained for the C16H10 added hot pressed sample is because of the homogenous C substitution into MgB2 grains, as compatible with its lower Δρ value, and thus increased flux pinning ability.
- MakaleAçık Erişim2024Scopus SJRQ2An optimization study for amino acid extraction from bee bread using choline chloride-acetic acid deep eutectic solvent and determination of individual phenolic profile
Kutlu, Naciye; Gerçek, Yusuf Can; Çelik, Saffet; Bayram, Sinan; Ecem Bayram, Nesrin
In this study, the aim was to optimize the extraction conditions (molar ratio, time, temperature) in order to maximize the total individual amino acid (TAA) yield from bee bread, which is a fermented bee product, using choline chloride-acetic acid deep eutectic solvent (DES). In addition to the phenolic profile and amino acid profile investigated by LC-MS/MS, some spectrophotometric (total phenolic content, total flavonoid content, total proanthocyanidin content) and bioactivity (antioxidant/antimicrobial activity) tests were carried out on the extracts. Optimum conditions were determined as 1:2 for molar ratio, 15 min for time and 10 °C for temperature with optimization based on the TAA values of the different extracts (d: 0.99). Molar ratio and temperature were found to have statistically significant effects on TAA values. At optimum conditions, the amount of TAA obtained with DES (29.678 g/kg) was found to be approximately 35.2% and 54.4% higher than that obtained with ethanol and methanol extracts, respectively. All these results indicate that choline chloride-acetic acid DES can be chosen when preparing bee bread extracts, which are evaluated for different areas of use such as food and health due to active ingredient content. Higher active ingredients can be extracted by trying different DES combinations.
AtıfScopus7WoS9OpenAlex11İncele - MakaleAçık Erişim2024Scopus SJRQ1An investigation of cyberloafing behaviors in learners of Turkish as a foreign language
Güngör, Haluk; Ustabulut, Mete Yusuf
Cyberloafing can be defined as using technological devices for extracurricular activities during the lesson. The misuse of technological tools and facilities in educational environments causes many learning problems. One of the most important behaviors that cause this problem is cyberloafing. The explorative and main aim of the current study is to examine the reasons behind the cyberloafing behaviors of those who learn Turkish as a foreign language in terms of various variables and explore the phenomenological point of view of participants. The research was carried out in accordance with the convergent parallel mixed method design. The “Cyberloafing Behaviors Scale” was employed to collect quantitative data from a total of 207 students learning Turkish in 5 different TÖMER (Teaching Turkish Center); in the process of qualitative data collection, open-ended questions formed by the researcher were used. For examining mean differences in terms of categorical variables t-test and separate ANOVAs were run. In ANOVAs, in order to minimize the possibility of error that may occur in the ANOVA test, type I error was controlled with Bonferroni correction. To determine predictors of cyberloafing behaviors of the study group multiple regression analysis was utilized. According to the findings of the current study, there was no significant difference between gender and time spent on social media and cyberloafing behavior; in the real-time updating dimension, it was determined that there was a significant difference between the B1 level and B2 and C1 levels. Having devices such as laptops stands out as the variable that predicts cyberloafing the most. It was also observed that cyberloafing behavior decreased as speaking skill increased. When the qualitative data was examined, the students stated that they were cyberloafing due to reasons such as messaging, sharing photos and videos because of boring lessons.
AtıfScopus3WoS4OpenAlex4İncele - MakaleYalnız künye2024Scopus SJRQ2Drought analysis using innovative trend analysis and machine learning models for Eastern Black Sea Basin
Niazkar, Majid; Piraei, Reza; Eryılmaz Türkkan, Gökçen; Hırca, Tuğçe; Gangi, Fabiola; Afzali, Seied Hosein
This study aims to assess the Eastern Black Sea Basin drought conditions. For this purpose, the trend changes in SPI values of 6, 9, 12, and 24 months using innovative trend analysis were examined. Additionally, four machine learning models, including Multiple Linear Regression, Artificial Neural Networks, K Nearest Neighbors, and XGBoost Regressor, are employed to forecast SPI with rainfall data between 1965 and 2020 from eight rainfall stations. The input data for each model was SPI values from lead times of 1 to 6, resulting into 768 unique scenarios. The ML models estimated SPI values better as the SPI duration increased, with the 24-month SPI showing the highest accuracy. The results of SPI forecast indicated that the optimal model and number of input variables varied for each SPI and station, indicating that further studies are required to improve SPI predictions.
AtıfScopus24WoS23OpenAlex25İncele - MakaleAçık Erişim2024Analysis of the nonlinear optical properties, vibrational spectra, DFT method and photovoltaic performance of cyanidin-3-rutinoside chloride
Sarıkaya, Ebru Karakaş; Ekincioğlu, Yavuz; Bahçeli, Semiha; Dereli, Ömer
This study aims to identify a cyanidin-3-rutinoside chloride that exhibits both photovoltaic performance and nonlinear optical properties, which may be utilized in the field of optoelectronics. Prior to investigating these properties, the stable structure must be determined. For this purpose, its conformational analysis is performed by the Molecular Force Field method with the spartan program. The exact nature of the stable configuration has been ascertained by empirical evidence. The energy of the stable configuration is -1654184.76 kcal/mol, and its dipole moment is 9.94 Debye. Cyanidin-3-rutinoside chloride has been investigated using experimental FT-IR and Raman spectroscopies. Meanwhile, the DFT method at the B3LYP/6-311 + + G(d, p) level was employed in order to study the simulated FT-IR and Raman spectra, the HOMO-LUMO analysis, the molecular electrostatic potentials (MEP), and the non-linear optical (NLO) characteristics of the title molecule. The HOMO and LUMO energies are − 6.45 and − 3.64 electron volts (eV), respectively, with a gap value of 2.81 eV. Additionally, the title compound’s open-circuit voltage, the transition density matrix light-harvesting efficiency, driving force, and binding energy were calculated with by taking photovoltaic cell properties into account. Furthermore, investigations of hole reorganization energy, electron reorganization energy, and total reorganization energy were carried out at the B3LYP/6-31G(d, p) level for the cyanidin-3-rutinoside chloride of interest. In addition, density of state calculations and NBO were made at the B3LYP/6-31G(d, p) level. We calculated the following values for LHE,,,,, and : 0.06, 2.45 eV, 0.20 eV, 0.56 eV, 0.50 eV, 0.57 eV and 1.06 eV, respectively.
AtıfScopus9WoS10OpenAlex12İncele - MakaleAçık Erişim2024Scopus SJRQ2Electrical properties of Al/CZTSe nanocrystal Schottky diode
Kişnişci, Z.; Özel, F.; Karadeniz, S.; Tuğluoğlu, N.; Özel, S.S.; Yüksel, Ö.F.
In this study, electrical changes in diode parameters of Schottky diodes that made of a kesterite semiconductor were examined under different temperatures. For this aim, Cu2ZnSnSe4 (CZTSe) nanocrystals were fabricated using the hot injection technique, and it was covered by spin coating on an ITO glass substrate. We was introduced the physical and structural analyses using scanning electron microscopy and X-ray spectroscopy. Current–voltage measurements were fulfilled at different temperature (from 100 to 325 K) under dark environment. It was observed that its electrical parameters were strongly affected by temperature.
AtıfScopus11WoS10OpenAlex10İncele - MakaleAçık Erişim2023Scopus SJRQ2Optimizing and investigating durability performance of sandy soils stabilized with alkali activated waste tuff-fly ash mixtures
Yilmaz, Fatih; Kuvat, Ahmet; Kamiloğlu, Hakan Alper
The search for alternative environmentally-friendly materials to Portland cement is increasing its importance in geotechnical engineering as in other fields. In this study, alkali activated waste volcanic tuff (BT) and fly ash (FA) utilized as an alternative to conventional binders. The specific objectives of this paper were to, (1) optimize fly ash, waste tuff and activator content using Response Surface Methodology (RSM), (2) investigate the UCS performance of the optimum amount of alkali-activated fly ash and waste tuff mixtures as a binder in soil stabilization by comparing with various codes, (3) characterize the optimized parameters, (4) examine durability performances of the samples. Optimum binder and activator content and effect of waste tuff on strength characteristics were evaluated statistically with RSM approach. XRF, XRD, FTIR analyses were performed to verify the synthesized alkali activated material in the inner structures of the optimized samples. The durability and mechanical properties of samples stabilized with alkali activated binders against soaking condition, wetting-drying and were investigated. Destructive and non-destructive methods were employed to examine mechanical and durability characteristics. Unconfined compression strength, strength reduction ratio, soil deterioration, and water absorption capacity was taken into account to evaluate durability performances. UCS values of the stabilized samples were compared with limit UCS values suggested by several standards. As a result of the study it was determined that alkali activated waste tuff and fly ash mixture shows significant mechanical and durability performance in soil stabilization, and capable to use as an alternative to conventional non-green binders.
AtıfScopus6WoS4OpenAlex8İncele