Sürdürülebilir Kalkınma Amaçları
Yazarlar
- Gul, Muhammet(20)
- Celik, Erkan(12)
- Mete, Suleyman(11)
- Serin, Faruk(10)
- ALMisned, Ghada(9)
- Güler, Ömer(8)
- Yucesan, Melih(8)
- Tekin, H.O.(7)
- Artuğer, Fırat(6)
- Utku, Anıl(6)
- Guler, Omer(5)
- Özkul, İskender(5)
- Şimşek, Telem(5)
- Acar, Ramazan(4)
- Basgoz, Oykum(4)
- Guler, Seval Hale(4)
- Şimşek, Tuncay(4)
- Bahceci, Ersin(3)
- Baykal, Duygu Sen(3)
- Başhan, Veysi(3)
- Canbay, Canan Aksu(3)
- Demirel, Hakan(3)
- Doğan, Gürkan(3)
- Ergen, Burhan(3)
- Gul, Ali Oktay(3)
- Güler, Seval Hale(3)
- Gülmez, Nihan(3)
- Karaduman, Oktay(3)
- Kavaz, Esra(3)
- Kaya, Sema Kayapinar(3)
- Onder Erguven, Gokhan(3)
- Yayla, Nihal(3)
- Yildirim, Nuran Cikcikoglu(3)
- Özkaynak, Fatih(3)
- Ak, M. Fatih(2)
- Albayrak, M. Gökhan(2)
- Aslan, Serpil(2)
- Aycin, Ejder(2)
- Can, Umit(2)
- Cemalgil, Selim(2)
Yayınlar
- MakaleYalnız künye2023Scopus SJRQ2Computer-aided Optimization of Geopolymer Mortars
Gülmez, Nihan; Koçkal, Niyazi Uğur
The optimum mix design of geopolymers involves the purpose of determining which mixture will have high engineering properties without compromising the importance of each variable. This experimental study aimed to investigate the effects of some critical geopolymer mixture parameters on engineering properties by using historical data design in response surface methodology (RSM). Statistical models were developed between factors (binder and aggregate content, curing conditions and aggregate type) and their response surfaces (oven dry (OD) bulk density, water absorption, compressive strength and flexural strength). The final mathematical models for the response surfaces were constructed in terms of coded factors defined as dimensionless. In addition, a multipurpose optimization technique was used to achieve the desired design with the desired maximum strength.
- MakaleAçık Erişim2023Scopus SJRQ2Application of the deep transfer learning framework for hydatid cyst classification using CT images
Gul, Yeliz; Muezzinoglu, Taha; Kilicarslan, Gulhan; Dogan, Sengul; Tuncer, Turker
Hydatid cyst, which causes important public health problems, is a disease frequently reported by radiologists. Classification of hydatid cyst types is very important to give the most suitable cure to patients. In order to decrease the misclassification rates of these cysts, machine learning is a good solution to create intelligent medical assistants. The primary objective of this work is to develop a new image classification framework to classify hydatid cyst types. Firstly, we collected a computed tomography (CT) image dataset. This CT image dataset consists of 2416 CT images with five classes (hydatid cyst types). We proposed a new deep feature engineering dataset framework for this dataset. This framework consists of (i) deep feature extraction by deploying transfer learning, (ii) iterative feature selection using INCA (iterative neighborhood component analysis), and (iii) classification. In the first phase—the feature extraction phase—we extracted deep features by deploying ten pretrained convolutional neural networks (CNNs). The used CNNs are commonly used CNNs, and the deep features have been extracted using the last pooling and fully connected layers of these networks. INCA has been applied to the generated deep features by each feature vector. k-nearest neighbors (kNN) classifier has been utilized to generate predicted values of these 10 CNNs using the selected features by INCA. Our proposed INCA-based deep feature extractor attained over 92% classification accuracy for each pretrained model. Our proposed framework reached over 92% classification accuracies, clearly demonstrating that our proposed framework is good image classification.
AtıfScopus10WoS5OpenAlex8
İncele - MakaleYalnız künye2023Scopus SJRQ2The Effect of Using Ferro-Alloy on the Properties of AlCoFeNiMoTi High-Entropy Alloy Produced by Arc-Melting Method: Design of Low Cost
Güler, Seval H.
The cost of high-entropy alloys (HEAs) is one of the most major obstacles to their widespread use. The cost of these alloys with significant amounts of five metals might reach very high levels depending on the type and quantity of metal utilised. Therefore, this study examined the effect of the use of ferro-alloys as part of the charge mixture on the properties of AlCoFeNiMoTi alloy. Ferro-alloys are much less expensive than the pure form of the same metal. To that end, two groups of samples were produced. The AlCoFeNiMoTi alloy was produced using high-purity metals as the metallic charge in the first group of samples. Instead of utilising the pure forms of some expensive metals that make up such alloy, as the metallic charge, lower-cost ferro-alloy forms were employed in the second group of samples. Following the preparation of the appropriate compositions, alloys were produced using the arc-melting method, and the produced alloys were subject to homogenization heat treatment. The obtained samples were characterised by X-ray diffraction (XRD) and scanning electron microscopy (SEM). Then, mechanical and corrosion tests were run. The corrosion resistance of the HEAs was compared with an electrochemical polarisation technique in a 3.5% NaCl electrolyte. It was observed that many intermetallics precipitated through the heat treatment of the samples, and the precipitates negatively affected the mechanical properties of the alloy. Also, in the samples in which ferro-alloy was used instead of pure metal, the mechanical properties were substantially degraded. This is believed to be associated with the presence of inclusions and other residues in ferro-alloys. Graphical Abstract: [Figure not available: see fulltext.]
AtıfScopus6WoS7OpenAlex7İncele - MakaleYalnız künye2022Scopus SJRQ1Experimental and material characterization of composites, including waste iron and marble powder
Gülmez, Nihan
Due to its fine particle size, waste marble slurry originating in cutting and processing units mixes into the air after drying, causing environmental and health problems in nearby areas. On the other hand, large amounts of iron particles are generated as metalworking industry waste, affecting the environmental system. In this study, 0%, 10%, and 20% marble powder (instead of cement) and iron particles (instead of fine aggregate) were used in mixtures, and the composites produced were subjected to two different curing periods: 7 and 28 days. The physical, mechanical, microstructural, and thermal properties of the fresh and hardened composites were ascertained via bulk density, consistency, porosity, water absorption, capillary water absorption, strength tests, particle size distribution, X-ray diffraction (XRF), X-ray fluorescence (XRF), scanning electron microscopy and energy dispersive spectroscopy (SEM–EDS), and thermogravimetric analyses (TGA). The results revealed that minimum water absorption (8.5%) and porosity (19.8%) values were achieved in 28-day composites produced with 10% marble–20% iron wastes among all composites. Thus, iron particles substituted for natural aggregates were mainly responsible for the increase in mechanical performance. A maximum flexural strength of 5.9 MPa and a compressive strength of 26.7 MPa were observed in 28-day composites containing 0% marble–20% iron wastes. Furthermore, capillary water absorption tended to decrease with the substitution of 10% marble powder.
AtıfScopus3WoS2
İncele - MakaleAçık Erişim2022Scopus SJRQ2Effect of Cu, Sn and Sb addition on the structural, thermal and magnetic properties of body-centered cubic structured CoNiMnGaSi high entropy alloy
Şimşek, Telem; Özkul, İskender; Canbay, Canan Aksu; Avar, Barış; Şimşek, Tuncay; Güler, Seval Hale; Özcan, Sadan; Güler, Ömer; Chattopadhyay, Arun K.
In this study structural, morphological, thermal and magnetic properties of equiatomic CoNiMnGaSi (base), CoNiMnGaSiCu, CoNiMnGaSiSn and CoNiMnGaSiSb alloys are discussed. The formation of solid-solution nanocrystalline bcc structure of the alloys was determined by XRD and DTA techniques. SEM–EDS analyses also revealed the homogeneous distribution of the elements. The room temperature magnetic hysteresis loops showed that as-casted alloys reached saturation easily with coercivity less than or equal to 35 Oe. As the Cu and Sn were added to the alloy, the saturation magnetization was decreased from 112 emu/g to 50 emu/g, which was mainly due to the substitution of non-magnetic atoms to the magnetic Co in the base CoNiMnGaSi alloy, whereas the addition of Sb to the base alloy did not have a significant effect on the Ms. The CoNiMnGaSiSb was found to have the highest Curie Temperature of 670 K, which makes the alloy a promising candidate for power industry-related applications.
AtıfScopus3OpenAlex4İncele - MakaleAçık Erişim2022Scopus SJRQ1Medical waste management during coronavirus disease 2019 pandemic at the city level
Polat, E.G.
Coronavirus disease 2019 brings about the economic damage and loss of life. Thus, demand of personal protective equipment continues to increase, consequently an increase in infectious equipment pollution. Most of these wastes threaten the environment and increase the spread of diseases. This paper provides a research hypothesis whether effective medical waste management would prevent the possible impacts of coronavirus disease 2019-related waste issues on environment at the city level. To confirm this hypothesis, installation of waste treatment centre is addressed. Then, by incorporating uncertain waste generation amounts utilizing Jimenez method, a pickup routing is addressed to decide the pickup routes between the waste treatment centre and residential area. This study is first to assign the optimistic, realistic and pessimistic scenarios of the uncertain waste generation using time series analysis method and waste generation formulation. Also, L-type matrix is used to define, assess and prioritize the environmental and operational risks on waste generation formulation and to provide risk reaction strategies. Practicality of these approaches is illustrated in the case of Turkey. The computational results reveal the effectiveness of the integrated method, which ensures practical and theoretical insights controlling the waste generation to prevent virus propagation for health authorities.
AtıfScopus15WoS13OpenAlex19İncele - MakaleYalnız künye2022Scopus SJRQ3The Effect of Using Waste Tire as a Fine Aggregate on Mechanical Properties of Fly Ash-Substituted Self-Compacting Concrete
Cemalgil, Selim
Wasted tyres are commonly used in civil engineering applications for a variety of purposes, including as concrete ingredients. Wasted tires that are mechanically sheared into shreds ranging in size from 25 to 300 mm and intended for use in concrete are called " Waste Shreded Tyre Aggregate" to make a contribution to sustainable waste management. Currently, at this point, the basic philosophy of this study is to investigate the effects of Waste Tire Aggregate (WTA) on the mechanical and durability properties of Self Compacting Concrete (SCC) to provide a contribution to reusing waste tires in the construction industry. WTAs with 5, 10, and 15% volume ratios are substituted for fine aggregate in SCC production. In addition, 15% mixtures with a binder quantity of 550 kg/m3, including 20 and 30% fly ash (FA) were substituted and prepared to be compared with the control concrete. To measure the rheological properties of SCCs, slump flow, V-funnel and L-box tests were performed. Then, the produced concrete samples of different sizes were cured under laboratory conditions for 28 days and then subjected to hardened concrete tests on the 28th, 56th and 90th days. The hardened concrete tests were composed of axial compressive strength, flexural strength, splitting tensile, diagonal tensile, abrasion resistance, modulus of elasticity. Finally, a durability test was performed as chlorine penetration depth. The test results show that WTA positively affects the properties of fresh and hardened SCC. Only, the increase in the substitution rate of WTA in concrete mixtures decreased the hardened state strength of the SCC. However, the addition of WTA to up to 15% of the total fine aggregate volume indicates that it is possible to apply recycled WTA to SCC and successfully satisfy both fresh and hardened SCC specifications.
AtıfScopus4WoS5OpenAlex4İncele - MakaleAçık Erişim2022Scopus SJRQ2Tangent hyperbolic non-Newtonian radiative bioconvection nanofluid flow from a bi-directional stretching surface with electro-magneto-hydrodynamic, Joule heating and modified diffusion effects
Prakash, J.; Tripathi, Dharmendra; Akkurt, Nevzat; Bég, O. Anwar
Motivated by bio-inspired nano-technological functional coating flows, in the current paper a theoretical study of laminar, steady, incompressible bioconvection flow of a tangential hyperbolic (non-Newtonian) nanofluid from a bi-directional stretching surface under mutually orthogonal electrical and magnetic fields is presented. Nonlinear thermal radiation, Joule heating and heat source/sink effects are included. Non-Fourier and non-Fickian models are also implemented which feature thermal and solutal relaxation. Buongiorno’s nanoscale model is adopted which features thermophoresis and Brownian motion effects. Rosseland’s model is employed for thermal radiation. The electro-viscous effects arising from the distortions of the double-capacitance electric flow field are addressed with a modified formulation of the Poisson–Boltzmann equation. Via appropriate similarity transformations, the coupled, nonlinear partial differential conservation boundary layer equations and wall and freestream boundary conditions are rendered into a nonlinear ordinary differential boundary value problem which is solved numerically with an efficient numerical Lobatto—IIIa collocation method available in the MATLAB bvp4c shooting solver. Validation with previous studies is included. Velocity is strongly damped with increasing buoyancy ratio and bioconvection Rayleigh number is generally greater with positive rather than negative electrical field parameter. Increasing the Eckert number reduces the density of motile microorganisms while raising the temperature. An increment in Brownian motion and radiative parameters strongly accentuates temperatures.
AtıfScopus36WoS33OpenAlex35İncele - MakaleAçık Erişim2022Scopus SJRQ2Optimization of Electrical Conductivity of SA-graphene Nanocomposites Using Response Surface Methodology
Şahal, Hakan; Torğut, Gülben; Canpolat, Erdal
Synthesis and characterization of 4-{(E)-[(5-bromo-2-hydroxyphenyl)methylidene]amino}-N-carbamimidoylbenzene-1-sulfonamide(SA) and its composites with graphene(SA-GF) were performed. Compound SA and SA-GF were characterized by FTIR and 1H NMR. The GF dispersion in the composites was analyzed by means of scanning electron microscopy(SEM) for morphology. Thermal properties of SA and nanocomposites were investigated using differential thermal analysis(DTA) and thermogravimetric analysis(TGA). The optimum electrical conductivity of the new sulfonamide-based Schiff base was determined to be 1.78×10−5 S/cm at a frequency of 9923 Hz, an applied voltage of −19 V, a mass fraction of 9.38% for graphene loading using a central composite design in the response surface methodology. The significance of the selected parameters(frequency, voltage and GF amount) in the model was determined by the analysis of variance(ANOVA). The results showed that frequency and graphene loading represent important model terms and have considerable effects on the conductivity of SA.
AtıfScopus3WoS3OpenAlex2İncele - MakaleAçık Erişim2022Scopus SJRQ1SBOX-CGA: substitution box generator based on chaos and genetic algorithm
Artuğer, Fırat; Özkaynak, Fatih
What makes artificial intelligence techniques so remarkable in the field of computer science is undoubtedly their success in producing effective solutions to difficult computational problems. In particular, metaheuristic optimization algorithms are a unique example of using artificial intelligence techniques to generate approximate solutions to problems that cannot be solved in polynomial time, called NP. Obtaining a substitution box (s-box) structure that will satisfy the desired requirements in cryptography is an example of these NP problems. In the literature, it is a hot topic to optimize the s-box structures obtained from chaotic entropy sources with heuristic algorithms to improve their cryptographic properties. The study with the highest nonlinearity value (110.25) based on optimization algorithms to date has been published in 2020. In this study, a method with a higher nonlinearity value than the algorithms previously proposed in the literature is developed. It has been shown that the nonlinearity value can be increased to 111.75. These results will be a basis for new research on the chaos-based s-box literature and will motivate new studies to develop alternative optimization algorithms in the future to obtain s-box structures based on the random selection equivalent to the AES s-box.
AtıfScopus47WoS35OpenAlex49İncele - MakaleYalnız künye2022Scopus SJRQ1Testing Simplified Beerkan Infiltration (SBI) Methods on Technosol to Estimate the Saturated Hydraulic Conductivity
Yilmaz, D.
The development of infiltration techniques has facilitated the estimation of soils hydraulic properties. Among these, the simplified Beerkan infiltration methods are the most attractive because of their ease of use and low cost. However, they have not been tested on a wide range of soils, more particularly on technosols which are more and more present in urban areas. The transient method using the preliminary part of the infiltration curve and the long-time method using the part of the curve where the infiltration flow becomes permanent were tested on 32 infiltrations collected on 5 experimental technosols to estimate the saturated hydraulic conductivity Ks. The results show that the estimated Ks for both methods are in the same order of magnitude when compared to the reference value. The steady state approach has led to better results of Ks estimates related with R2 factor of 0.902 versus 0.798 for transient one. However, in the case of Basic Oxygen Furnace slag technosol the differences in Ks estimates are more pronounced and additional investigations are necessary. If no complex reaction inside the microstructure occurs, then the simplified method may be used for a rough estimate of Ks on technosols.
AtıfScopus1WoS1OpenAlex1İncele - DüzeltmeAçık Erişim2022Scopus SJRQ2Correction to: Boron nitride nanosheet-reinforced WNiCoFeCr high-entropy alloys: the role of B4C on the structural, physical, mechanical, and radiological shielding properties (Applied Physics A, (2022), 128, 8, (694), 10.1007/s00339-022-05813-5)
Kavaz, Esra; Gul, Ali Oktay; Basgoz, Oykum; Guler, Omer; ALMisned, Ghada; Bahceci, Ersin; Guler, Seval Hale; Tekin, H.O.
In this article the affiliation 7 was incorrectly assigned to all authors but H.O. Tekin.
AtıfScopus1İncele - MakaleAçık Erişim2022Scopus SJRQ2Health, safety, and environmental failure evaluation by hybridizing fuzzy multi-attribute decision-making methods for maritime scrubber systems
Başhan, Veysi; Yucesan, Melih; Demirel, Hakan; Gul, Muhammet
Many shipping companies have started using scrubbers in their fleet to eliminate sulfur emissions from ships, per IMO (International Maritime Organization) rules. Before and during the scrubbers’ selection, the scrubbers’ operational failures have also started to appear and cause serious concerns. In this study, classified scrubber types are explained and open type, closed type, and hybrid scrubber systems are evaluated. To contribute to this gap in the literature, scrubber failures were identified, five experts with different perspectives were consulted, and the most common and critical malfunctions were evaluated with the fuzzy best–worst method (F-BWM) and fuzzy technique for order preference by similarity to an ideal solution (F-TOPSIS). F-BWM was used to determine the importance weights of the risk parameters used in evaluating failures since it provides fewer comparisons among pairwise comparison–based decision-making methods and a more consistent judgment in the evaluation. F-TOPSIS, on the other hand, was used to determine the final priority scores of the scrubber failures, taking into account the risk parameter weights obtained in the first stage. It has been preferred due to its easy to useness and based on its closeness to the ideal solution and applicability to risk and failure analysis problems. Considering all different systems in general, important issues such as collection efficiency, sulfur emission problem, abrasion, leakages, pump failures, heat exchanger failures, air fan sealing failures, sensors and failures in monitoring the whole system have been investigated. Results show that too high axial velocity for separator and flooded separator, too high solids concentration in recirculation liquid (SF2), piping leakages (SF5), poor quality or inappropriate consumables and chemicals (SF11), and feed circulation pump problems (SF6) are found to be the most important problems among thirteen failures.
AtıfScopus23OpenAlex23İncele - MakaleAçık Erişim2022Scopus SJRQ1Control measure prioritization in Fine − Kinney-based risk assessment: a Bayesian BWM-Fuzzy VIKOR combined approach in an oil station
Gul, Muhammet; Yucesan, Melih; Ak, Muhammet Fatih
The Fine − Kinney is a risk assessment method widely used in many industries due to its ease of use and quantitative risk evaluation. As in other methods, it is a method that recommends taking a series of control measures for operational safety. However, it is not always possible to implement control measures based on the determined priorities of the risks. It is considered that determining the priorities of these measures depends on many criteria such as applicability, functionality, performance, and integrity. Therefore, this study has studied the prioritization of control measures in Fine − Kinney-based risk assessment. The criteria affecting the prioritization of control measures are hierarchically structured, and the importance weights of the criteria are determined by the Bayesian Best–Worst Method (BBWM). The priorities of control measures were determined with the fuzzy VlseKriterijumska Optimizacija I Kompromisno Resenje (FVIKOR) method. The proposed model has been applied to the risk assessment process in a petrol station’s liquid fuel tank area. According to the results obtained with BBWM, the most important criterion affecting the prioritization of control measures is the applicability criterion. It has an importance weight of about 42%. It is followed by performance with 31%, functionality with 18%, and integrity with 10%, respectively. FVIKOR results show that the “Periodic control of the ventilation device” measure is the top priority for Fine − Kinney risk assessment. “The absence of any ducts or sewer pits that may cause gas accumulation in the tank area and near the dispenser; Yellow line marking of entry and exit and vehicle roads; Placing of speed limit warning signs” has been determined as a secondary priority. On conclusion, this proposed model is expected to bring a new perspective to the work of occupational health and safety analysts, since the priority suggested by Fine − Kinney risk analysis methods is not always in the same order as the one in the stage of taking action, and the source, budget, and cost/benefit ratio of the measure affect this situation in practice.
AtıfScopus51WoS42OpenAlex54İncele - MakaleAçık Erişim2022Scopus SJRQ1A green algae Cladophora fracta for accumulation of toxic/harmful pollutants causing environmental pollution in mine gallery waters
Topal, M.; Arslan Topal, E.I.; Öbek, E.
In the present study, the bioaccumulation of toxic/harmful pollutants (Fe, Pb, As, Cd, Cr, Ba, and Mn) by Cladophora fracta in mine gallery water was investigated. For this aim, the reactors planted with C. fracta were placed into mine gallery waters. Bioconcentration factor (BCF), metal pollution index (MPI), and accumulation capacity values were determined. According to the obtained results, the highest concentrations of Cr, Mn, Fe, Ba, Pb, Cd, and As were determined as 24.3 ± 1.2, 858 ± 27, 26,290 ± 87, 11.4 ± 0.6, 117.05 ± 5.8, 47.9 ± 1.4, and 2390.3 ± 11 mg/kg, respectively. BCF values were Fe > Pb > As > Cd > Cr > Ba > Mn. The MPI values of toxic/harmful pollutants according to days were determined as day 1 > 5 > 7 > 2 > 6 > 4 > 3, respectively. As a result, it was determined that C. fracta, which was placed in the mine gallery and exposed to the gallery waters, was effective in removing toxic/harmful pollutants. Therefore, C. fracta can be used as an alternative treatment material for the removal of toxic/harmful pollutants in mine gallery waters.
AtıfScopus4WoS3OpenAlex5İncele - MakaleYalnız künye2022Scopus SJRQ1Occupational health, safety and environmental risk assessment in textile production industry through a Bayesian BWM-VIKOR approach
Ak, M. Fatih; Yucesan, Melih; Gul, Muhammet
Occupational risk assessment (ORA) is a process that consists of evaluating, ranking, and classifying the hazards and associated risks arising in any workplace from the viewpoint of occupational health and safety. Many ORA methods have been proposed in the literature, from a single independent expert to participatory methodologies made by group decision and simple to complex ones. In this paper, a holistic ORA is presented, which uses two important multi-attribute decision methods named Bayesian Best-Worst Method (Bayesian BWM) and VIseKriterijumska Optimizacija I Kompromisno Resenje (VIKOR). Bayesian BWM is used to determine the importance weights of six different assessment criteria, which are the probability of hazardous event (P), frequency (F), severity (S), detectability (D), cost (C) and sensitivity not to use personal protective equipment (SNP). Since the classical BWM finds solution to the weights of a number of criteria from only one expert's judgment, Bayesian BWM is preferred in this paper (1) to enable participation of a group of experts, (2) to aggregate the preferences of these multiple experts into consensus without loss of information and (3) to follow a probabilistic way for solving the ORA problem. The hazards are then ranked by VIKOR. The approach is implemented in the ORA process of a textile production plant. Results of risk analysis showed that electricity hazard and associated risks constitute the highest risk ratings. These hazards arise from the product, process, human and working environment. The associated risks are evaluated, prioritized, and detailed control measures are proposed. This study made comparisons with the classical BWM-VIKOR approach to demonstrate the proposed approach's difference and practicality. Results can also help practitioners and risk analysts in formulating the improvement measures to increase the overall safety of the working environment further.
AtıfScopus87WoS78OpenAlex87İncele - MakaleAçık Erişim2022Scopus SJRQ2Synthesis and characterization of N-(2-acetyl benzofuran-3-yl) methacryl amide and ethyl methacrylate copolymer/graphite oxide composites and study of their kinetic and electrical properties
Demirelli, Kadir; Barım, Esra; Tuncer, Hülya; Barım, Gamze; Abubakar, Abdullahi Musa
Copolymers of N-(2-acetylbenzofuran-3-yl) methacrylamide (BFMAA) and ethyl methacrylate (EMA) were prepared by radical copolymerization. The composition of copolymers was estimated by 1H-NMR spectroscopy. The composites of P(BFMAA39-co-EMA) [COP1] and P(BFMAA15-co-EMA) [COP2] loaded 18 wt% graphite oxide (GO) were prepared utilizing Ultrasonic Homogenizer Sonicator Processor. The FT-IR, DSC, TGA and SEM techniques were used in the characterization of the copolymers and composites. The thermal degradation behavior of COP1 was investigated by FT-IR studies of the partially degraded copolymer. And, this copolymer was able to form a four-member amide ring and imidization via intramolecular while being heated above 340 °C. Dynamic TG analysis under argon gas was used to investigate the thermal decomposition processes of pure COP1 and COP1/GO. Two degradation models including the Flynn–Wall–Ozawa and Kissinger–Akahira–Sunose methods were used to determine the apparent activation energy of the copolymer and its composite for approximately 65% of thermal decomposition occurred between 200 and 400 °C. The results also showed that average activation energy between 111.69 and 134.25 kJ/mol was obtained. The estimated activation energy values make it possible to build a simpler approach to expose the thermal decomposition behavior of copolymer and its composite. Dielectric and electrical behaviors of the copolymer composites having a semiconductor behavior filled with graphite oxide (GO) were investigated. The activation energy values of P(BFMAA15%-co-EMA)[COP2]/GO 18 wt% and COP1/GO 18wt% from dc conductivities were 0.182 eV and 0.245 eV, respectively.
AtıfScopus6OpenAlex8İncele - MakaleYalnız künye2022Scopus SJRQ2Characterization of the mechanical and thermal properties of rape short natural-fiber reinforced thermoplastic composites
Kısmet, Yılmaz; Dogan, Akar
In this study, the effects of filler amounts were studied on the mechanical and thermal properties of high-density polyethylene (HDPE), polystyrene (PS) and polyoxymethylene (POM) polymers reinforced with short rape fibers. HDPE-rape, POM-rape and PS-rape fiber composite materials were prepared with different fiber contents and their tensile, flexural, Izod impact and TGA/DTA properties were examined. When tensile and Izod impact properties were compared, it was observed that an increase in the amount of filling in HDPE-based composites did not cause any significant changes in these peoperties, while they were decreased for POM- and PS-based composites. On the contrary to tensile and impact strengths, when the three-point flexural properties were examined, it was observed that the strength values of all these materials increased with increasing the amount of fillers. However, a pronounced increase was observed in the three-point flexural strength of the HDPE-based composite materials. The flexural strength of 30 wt% rape-reinforced HDPE composite was found to be twice that of the pure HDPE. The results of TGA and DTA analyses revealed that the reinforcement element started to burn before the matrix material and therefore burning was delayed in these thermoplastics. As a result, the mechanical properties of HDPE composite materials improved with rape reinforcement. In this way, by using approximately 30 wt% natural filling material in a polymeric matrix, an environmentally friendly material, as well as, significant advantages in cost can be obtained. Graphic abstract: [Figure not available: see fulltext.].
AtıfScopus25WoS25OpenAlex33İncele - MakaleYalnız künye2022Scopus SJRQ2Boron nitride nanosheet-reinforced WNiCoFeCr high-entropy alloys: the role of B4C on the structural, physical, mechanical, and radiological shielding properties
Kavaz, Esra; Gul, Ali Oktay; Basgoz, Oykum; Guler, Omer; ALMisned, Ghada; Bahceci, Ersin; Guler, Seval Hale; Tekin, H.O.
The synthesis and extensive characterization of newly developed boron nitride nanosheet (BNNSs)-reinforced WNiCoFeCr high-entropy alloys (HEAs) are presented. The influence of B4C on the structural, physical, mechanical, and nuclear shielding characteristics of synthesized HEAs has been widely examined in terms of its monotonic effects on the behavior changes. The internal morphology and structural characteristics of the fabricated composites are first investigated using X-ray diffraction, scanning electron microscopy, and energy-dispersive spectroscopy. Wear testing is used to determine the coefficient of friction as a function of sliding distance. Experimental gamma ray and neutron setups are created to determine their shielding characteristics against nuclear radiation. Finally, the shielding characteristics of nuclear radiation for gamma ray and fast neutrons are compared extensively to those of many existing and new-generation shielding materials. Among the examined samples, the S2 sample with B4C and BNNSs reinforcement had the greatest mechanical characteristics. Our findings imply that increasing B4C directly contributes to the shielding qualities of nuclear radiation. The B4C created in the structure of BNNSs contributes to the overall properties of HEAs, which are crucial for nuclear applications, since HEAs are being examined as a component of future nuclear reactors. Additionally, B4C is a very versatile material that may be used in circumstances where mechanical and nuclear shielding properties need to be enhanced for a variety of radiation energies.
AtıfScopus11OpenAlex12İncele - MakaleAçık Erişim2022Scopus SJRQ1Aroclor 1254 impairs sperm quality, fertilization ability, and embryo development of rainbow trout (Oncorhynchus mykiss)
Kocabaş, Mehmet; Kocabaş, Filiz Kutluyer; Aksu, Önder; Benzer, Fulya; Erişir, Mine; Sahilli, Yeliz Çakir
The polychlorinated biphenyls (PCBs) in aquatic environment adversely affect non-target organisms, including fish. Especially, the male reproduction and next generation can be damaged through high exposure to these pollutants. Hence, the sperm cells were exposed to sublethal concentrations of Aroclor 1254 (0, 1, 5, 10, or 25 mg/l) for 4 h. The sperm quality parameters were analyzed by SCA (Sperm Class Analyzer). The fertility, eyeing, and hatching rates were determined as gamete markers. Lipid peroxidation (malondialdehyde-MDA), glutathione (GSH), and antioxidant enzymes [superoxide dismutase (SOD), glutathione peroxidase (GPx), and catalase (CAT)] were measured for determination of oxidative stress. Our results showed that Aroclor 1254 negatively affected the motility rate and duration, fertilization rate, embryogenesis, and hatching and also triggered antioxidant defense mechanisms at the highest concentration (25 mg L−1). Furthermore, linear speed (VSL), linearity index (LIN), and amplitude lateral head (ALH) were significantly changed after exposure to 25 mg L−1, and the lowest concentrations (1 and 10 mg L−1) did not significantly affect the motility and fertilizing capacity. The embryogenesis and hatching were significantly affected by sperm exposure to 1, 10, and 25 mg L−1 of Aroclor 1254. Consequently, Aroclor 1254 causes potential hazards in male germ cells, and the exposure of sperm cells to pollutants can adversely affect next generation of wild populations.
AtıfScopus6WoS5OpenAlex4İncele