Sürdürülebilir Kalkınma Amaçları
Yazarlar
- Dertli, Enes(11)
- Mercan, Emin(10)
- Ustabulut, Mete Yusuf(10)
- Ayata, Ümit(9)
- Kaya, Yunus(9)
- Sert, Durmuş(9)
- Ertugrul, Mehmet(8)
- Hasar, Ugur Cem(6)
- Tozlu, Alperen(6)
- Öner, Erdal(6)
- Abdioglu, Murat(5)
- Aktaş, Esat(5)
- Arslaner, Ayla(5)
- Bayram, Ozkan(5)
- Bulut, Mehmet(5)
- Ecem Bayram, Nesrin(5)
- Gürleyen, Levent(5)
- Karaduman, Ruken(5)
- Kaya, Feridun(5)
- Kul, Sinan(5)
- Türkmen, Mutlu(5)
- İspirli, Hümeyra(5)
- Artar, Musa(4)
- Arı, Ari(4)
- Azili, Kenan(4)
- Azimkhani, Amin(4)
- Bayraktar, Bülent(4)
- Dayı, Özkan(4)
- Gül, Volkan(4)
- Izginli, Mucahit(4)
- Kaban, Abdullatif(4)
- Kalay, Erbay(4)
- Kuzey, Memet(4)
- Ozdemir, Gazi(4)
- Ozturk, Gokhan(4)
- Ozturk, Hamdullah(4)
- Ozturk, Kemal(4)
- Saatchian, Vahid(4)
- Sarikaya, İsmail(4)
- Tekce, Emre(4)
Yayınlar
- MakaleYalnız künye2021Scopus SJRQ3Regioselective asymmetric bioreduction of trans-4-phenylbut-3-en-2-one by whole-cell of Weissella cibaria N9 biocatalyst
Kalay, Erbay; Şahin, Engin
There is a considerable interest in the asymmetric production of chiral allylic alcohols, the main building blocks of many functional molecules. The asymmetric reduction of α,β-unsaturated ketones is difficult with traditional chemical protocols in a regioselective and stereoselective manner. In this study, the reductive capacity of whole cell of Leuconostoc mesenteroides N6, Weissella paramesenteroides N7, Weissella cibaria N9, and Leuconostoc pseudomesenteroides N13 was investigated as whole-cell biocatalysts in the enantioselective reduction of (E)-4-phenylbut-3-en-2-one (1). The biocatalytic reduction of 1 to (S,E)-4-phenylbut-3-en-2-ol ((S,E)-2) using the whole cell of W. cibaria N9 isolated from Turkish sourdough was developed in a regioselective fashion, occurring with excellent conversion and recovering the product in good yield. In biocatalytic reduction reactions, the conversion of the substrate and the enantiomeric excess (ee) of the product are significantly affected by optimization parameters such as temperature, agitation rate, pH, and incubation time. Effects of these parameters on ee and conversion were investigated comprehensively. In addition, to our knowledge, this is the first report on production of (S,E)-2 using whole-cell biocatalyst in excellent yield, conversion with enantiopure form and at gram scale. These findings pave the way for the use of whole cell of W. cibaria N9 for challenging higher substrate concentrations of different α,β-unsaturated ketones for regioselective reduction at industrial scale.
AtıfScopus21WoS21OpenAlex23
İncele - MakaleAçık Erişim2021Scopus SJRQ1Optimum design of cold-formed steel frames via five novel nature-inspired metaheuristic algorithms under consideration of seismic loading
Carbas, Serdar; Artar, Musa
In this paper, an unbiased comparative assessment scheme for algorithmic performances of five novel nature-inspired metaheuristic algorithms in design optimization of steel frames made out of cold-formed steel sections under consideration of seismic loading is presented. These contemporary algorithms are so-called tree seed, squirrel search, water strider, grey wolf, and brain storm optimization. The functionality of the proposed algorithms is appraised with respect to design precisions in both portal and space cold-formed steel frames formulated according to the design provisions implemented by AISI-LRFD (American Iron and Steel Institute-Load and Resistance Factor Design). The cross-sectional dimensions of steel profiles, which are selected from available set of cold-formed thin-walled single-C sections, are treated as design variables in the optimization process in order to minimize the structural weight of the frames. In addition to specification constraint requirements, lateral and vertical displacement restrictions of the structural elements required for stability of the frames are also taken into account. Design optimization algorithms necessitate the structural response of cold-formed steel frames under load combinations including seismic loading effects which is accomplished by utilizing the open application programming interface (OAPI) mastery of MATLAB with SAP2000. The design optimization of cold-formed steel frames that is a discrete nonlinear programming problem reveal the robustness and applicability of proposed contemporary nature-inspired metaheuristic algorithms in real-sized complex structural optimization problems.
AtıfScopus15WoS15OpenAlex16İncele - MakaleAçık Erişim2021Scopus SJRQ1The investigation of flood risk perception as a quantitative analysis from socio-demographic perspective
Eryılmaz Türkkan, Gökçen; Hırca, Tuğçe
The priority of flood management planning is physical victimization and focuses on taking structural measures. Although this approach is an accurate approach, more information is needed in implementing efficient precautionary and planning decisions. It is an indisputable fact that the existence of nothing that is not sustainable in nature cannot continue. Hence, it is necessary to implement a planning decision suitable for the structure of the population living in the region so that the continuity of the policies to be carried out against natural hazards of hydrometeorological origin such as a flood is ensured. How the socio-demographic structures affect the flood risk perception of 245 people living in the city center of Bayburt is examined in this study. It is the first research conducted for the province of Bayburt for this perspective. The participants were asked to fill a questionnaire containing 24 items and consisting of 2 sections. T test and one-way ANOVA (one-way analysis of variance) statistical methods were used to ascertain the difference between the responses of the participants to the questionnaire, based on their demographic structure. As the result of the study, significant differences were observed between the expressions depicting flood risk perception and the participant's age, income levels and educational background. In addition, it has been noted that there is a positive relationship between education and income levels and flood risk perception.
AtıfScopus30WoS23OpenAlex39İncele - MakaleAçık Erişim2021Scopus SJRQ1Seed-propagated summer apples: Great morphological and biochemical diversity
Karatas, Neva; Ercisli, Sezai; Bozhuyuk, Mehmet Ramazan; Cakir, Ozlem; Necas, Tomas; Ondrasek, Ivo
The northeastern Anatolia region of Turkey is one of the richest plant biodiversity areas in Turkey. This study describes some important tree and fruit characteristics of 20 seed-propagated summer apple genotypes from northeastern Anatolia using morphological and biochemical markers. The genotypes were evaluated morphologically for tree growth habit, ripening date, fruit weight, fruit firmness, fruit shape, fruit color, fruit taste, juiciness and aroma. The biochemical characteristics measured were organic acids, SSC (soluble solid content), titratable acidity, vitamin C, total phenolic content and antioxidant capacity. We found significant differences for most of the morphological and biochemical characteristics. The genotypes exhibited quite diverse harvest dates ranging from 4 July to 16 August. Summer apple genotypes had fruit weight between 101.9 g and 133.5 g. The genotypes had diverse fruit shapes, including round, conic and oblate, and over fruit colours such as pink, red, yellow and green. Genotypes GUM7 and GUM13 stood out for fruit weight, SSC, total phenolic and antioxidant capacity. GUM7 and GUM13 present dissimilarity from the other genotypes. While the first showed a lower average fruit weight, SSC, total phenolic content and antioxidant capacity, the second revealed higher average of fruit weight, total phenolic content, antioxidant capacity and higher SSC. Due to their favorable characteristics, GUM13 can be used for further crosses with genotypes of other groups, which also present favorable characteristics.
AtıfScopus1WoS1OpenAlex1İncele - MakaleAçık Erişim2021Scopus SJRQ2Hybrid tabu search algorithm for weight optimization of planar steel frames
Tayfur, Bilal; Yilmaz, Hamid; Daloğlu, Ayşe T.
In this study, a hybrid metaheuristic algorithm called Hybrid Tabu Search (HTS) is proposed for the weight optimization of planar steel structures. The effectiveness of HTS lies in improving the initial conditions of a tabu search algorithm with a greedy search algorithm and a swap operator used in the phase of section selection. The effectiveness of the proposed method is tested and validated on three different benchmark examples. C♯ software is developed to perform the structural analyses. Numerical results obtained by using HTS showed that the proposed method achieved significantly lighter frame weights in most of the benchmark examples. When the method was examined in terms of computational efficiency, HTS was at a level that can compete with other algorithms examined within this study, although it did not provide a significant advantage.
AtıfScopus17WoS15OpenAlex15İncele - MakaleAçık Erişim2021Scopus SJRQ2An I-optimal experimental design-embedded nonlinear lexicographic goal programming model for optimization of controllable design factors
Ozdemir, Akin
Optimal experimental designs are effective offline quality improvement techniques used to enhance existing products and develop new products for a constrained design region. For some practical situations, I-optimal experimental designs may be the most suitable way to construct optimal experimental design points, by addressing prediction variance to generate a measure of prediction performance over the non-standard experimental design region. The purpose of this article is three-fold: (1) the I-optimality criterion is selected for minimizing the average prediction variance; (2) fitted mean and variance response models are found; and (3) a nonlinear lexicographic goal programming model incorporating an I-optimal experimental design is proposed to find the optimum settings of controllable design factors. Comparison studies and a numerical example are provided to illustrate the effectiveness of the proposed methodology for improvement of the quality of products.
AtıfScopus15WoS15OpenAlex16İncele - MakaleAçık Erişim2021Scopus SJRQ3Validity and reliability of the Turkish version of the insomnia catastrophizing scale
Kabadayi, Fedai; Mercan, Oğuz; Yazici-Kabadayi, Sema; Elhatip, Yaser Emir; Büyüksevindik, Baki
Insomnia catastrophizing has attracted attention in recent years. Individuals may have started to recognize the importance of evaluating the consequences of insomnia, which has worsened during the coronavirus disease 2019 (COVID-19) pandemic. The present study aimed to test the validity and reliability of the Insomnia Catastrophizing Scale (ICS) in the Turkish young adult population. The study group consisted of a total of 387 participants: 57 in the pilot study and 330 in the main study. The majority of the participants in the study were females. According to the results of the confirmatory factor analysis, the single-factor structures of the ICS nighttime and daytime forms were confirmed to be the same as in the original structure, and the fit indices were above the acceptable limits. The ICS forms had very high reliability. The findings of the present study showed that the Turkish daytime and nighttime forms of the ICS are valid and reliable instruments. The results provide a means of measuring insomnia catastrophizing for use in therapeutic and counseling settings for Turkish young adult population. We also propose that mental health practitioners should design interventions to reduce insomnia catastrophizing in Turkish culture.
AtıfScopus6WoS5OpenAlex5İncele - MakaleAçık Erişim2021Scopus SJRQ1Parameter Retrieval of Samples on a Substrate from Reflection-Only Waveguide Measurements
Hasar, Ugur Cem; Ozturk, Hamdullah; Kaya, Yunus; Izginli, Mucahit; Ertugrul, Mehmet
A microwave method has been proposed for constitutive parameters' extraction of samples on a known substrate. The advantage of this method is that it relies on noniterative reflection-only (air-and metal-backed) scattering (S-) parameters so that it is a good candidate for the characterization of samples when only one-port measurements are available. It is validated by the X-band (8.2-12.4 GHz) waveguide S-parameter measurements. A sensitivity analysis is followed to evaluate and improve the performance of our method.
AtıfScopus5WoS5OpenAlex3İncele - MakaleAçık Erişim2021Scopus SJRQ3Optimization of Extraction Parameters of Ethanol Extracts of Propolis Samples Using Artificial Neural Network and Moth-Flame Optimization Algorithm
Gurgen, Ayşenur; Serencam, Huseyin; Kara, Yakup; Can, Zehra; Ylldlz, Sibel
In this study, the optimum values of propolis ethanol extracts parameters were determined with the use of single and multi-objective optimization procedures. The euclidean distance approach was used in the multi-objective optimization process. Firstly, propolis was extracted using water with ethanol contents 40, 50, 60, 70 and 80% for 8, 10, 12, 16, 20 and 24 h. Then, total phenolic content (TPC) and ferric reducing antioxidant power (FRAP) activities of all extracts were determined. With the obtained data a prediction model was produced with the use of artificial neural networks (ANN), and optimization was performed using a moth-flame (MFO) algorithm. The best prediction models for the TPC and FRAP were observed in 2-5-1 and 2-5-1 network architecture with the mean absolute percentage error (MAPE) values, 5.126 and 2.451%, respectively. For maximum TPC, the extraction parameters were determined as ethanol content 57.5% and extraction time 13.56 h. To maximize FRAP, the optimized extraction parameters were ethanol content 72.03% and extraction time 18.04 h. The optimum extraction conditions for both maximum values of the studied assays were ethanol content 70.03% and extraction time 16.93 h. The study concluded that the integrated ANN and MFO algorithm system can be used in single and multi-objective optimization of extraction parameters. The established optimization model can save time, money, labor and energy.
AtıfScopus1WoS1OpenAlex1İncele - MakaleAçık Erişim2021Scopus SJRQ2Effect of ohmic heating on ultrasound extraction of phenolic compounds from cornelian cherry (Cornus mas)
Kutlu, Naciye; Isci, Asli; Sakiyan, Ozge; Yilmaz, Asim Egemen
In this study, total phenolic compounds (TPCs) from cornelian cherry were extracted by using maceration (ME), ultrasound extraction (UE), and ohmic heating-assisted ultrasound extraction (OAUE) methods. ME was used as a control group. It was observed that the ultrasound was effective on the yield of TPC in extraction and the effect was increased when this method was supported with ohmic heating (OH). The maximum TPC extracted was found to be 7.52 mg GAE/g dry matter (by using OAUE) which was 13% and 37% higher compared with that of obtained by UE and ME, respectively. It was also observed that the ohmic heating application decreased the extraction time by about 34% compared with UE. Moreover, the extracts obtained by OAUE had the highest total monomeric anthocyanin concentration and antioxidant activity. Consequently, the OH application prior to extraction played an active role in both obtaining the valuable compounds and decreasing the extraction time. Practical applications: Cornelian cherry (Cornus mas), which is a natural antioxidant source, contains a significant number of valuable compounds (polyphenols, vitamins, minerals, etc.). Therefore, new extraction methods were used as an alternative to conventional methods (such as maceration) to extract the valuable compounds. It was observed that novel methods such as ultrasound and ohmic heating-assisted extraction had a positive effect to increase extraction yield and saving time. Highly efficient applications (such as ohmic heating) on the extraction of bioactive compounds from food materials open up a new horizon in the food industry.
AtıfScopus35WoS33OpenAlex35İncele - MakaleAçık Erişim2021Scopus SJRQ4Investigation of the relationship of asprosin and cardiac troponin response with some physiological and biochemical parameters in Anatolian native horse
Bayraktar, Bülent; Tekce, Emre
Summary: Asprosin is a recently discovered glucogenic hormone released from starvation-induced white adipose tissue and amongst others it protects against hyperinsulinism associated with metabolic syndrome. The aim of this study was to examine the effect of age, gender and season on metabolic (asprosin) and cardiovascular (cardiac troponin, I (cTnI), CK, CK-MB) function markers and their relationship with some biochemical parameters in Anatolian native horse breed. This study was carried out between February–August 2020. A total of 40 horses was used for this purpose, including 20 mares and 20 stallions in the age range of 1–6, 7–12. Serum asprosin level, for the winter season in stallions and mares aged 1–6 and 7–12 years respectively 8.9, 8.36; 14.08, 13.58ng/ml were as determined. In addition, for the summer season respectively 17.98, 18.68; 22.22, 21.32ng/ml were detected and no difference between the groups (P>0.05). On the other hand, serum cTnI levels for the winter season in stallions and mares aged 1–6 and 7–12 years respectively 0.014, 0.018; 0.016, 0.02ng/ml were as determined. In addition, for the summer season respectively 0.012, 0.016; 0.014, 0.018ng/ml were detected. It was shown that the serum biochemical parameters and levels of cTnI levels in the domestic horse breed the horses belonging to the Anatolian varied depending on age, gender, and season (p < 0.05) but the effect of hormone levels serum asprosin wasn’t found statistically significant (p>0.05).Our results showed that cTnI could be a useful parameter in the examination of the cardiovascular system status of horses.
AtıfScopus1WoS1OpenAlex1İncele - MakaleAçık Erişim2021Scopus SJRQ1Prediction of water-adulteration within honey by air-line de-embedding waveguide measurements
Hasar, Hafize; Hasar, Ugur Cem; Kaya, Yunus; Ozturk, Hamdullah; Izginli, Mucahit; Ozbek, Ibrahim Yucel; Oztas, Taskin; Canbolat, Mustafa Yildirim; Ertugrul, Mehmet
An efficient de-embedding air-line microwave method has been proposed for accurate relative complex permittivity, εr=εr′−iεr′′, measurement of water-adulteration level within honey. It could be effectively applied to eliminate the errors arising from usage of imperfect calibration standards because it bypasses the requirement of these standards. Its accuracy is improved by utilizing the unitary and similarity properties of a passive two-port network, and then is compared with the accuracy of a calibration-dependent method present in the literature by using normalized root-mean-square-error (N-RMSE) values of εr′ and εr′′ of distilled water, in reference to the Debye value. From this comparison, it is observed that N-RMSE values calculated for εr′ (and εr′′) by using this calibration-dependent method and the (improved) proposed method are, respectively, around 0.1955 (0.1002) and 0.1962 (1.1067), indicating a good agreement between them. After validation the proposed de-embedding method using distilled water measurements, tested pure honey was adulterated with distilled water by different percentage values δ ranging from 1% to 10% in 1% increments. It is observed that the maximum distance between extracted εr′ (or εr′′) values of adulterated honey by the applied calibration-dependent method and the proposed method is less than 2%. Afterward, an empirical formula was devised to fit εr′ and εr′′ values from measured εr of water-adulterated honey with various δ levels. It is noted that extracted εr′ is much more better fitted than extracted εr′′, especially for δ≤4. Next, an optimization process is followed to evaluate the frequency for optimum prediction of adulteration levels using the empirical formula based on εr′ or εr′′. It is noticed that optimized δ values using the empirical formula based on εr′ (with an average prediction error of around 0.071 at 4.5 GHz) are superior to optimized δ values using the empirical formula based on εr′′ (with an average prediction error of around 0.085 at 4.2 GHz) for prediction of previously known δ values. Sensitivity and uncertainty analyses were performed to assess and improve the accuracy of the proposed method.
AtıfScopus24WoS23OpenAlex24İncele - MakaleAçık Erişim2021Scopus SJRQ2Gamma-ray irradiation effects on capacitance and conductance of graphene-based Schottky diode
Efil Kutluoğlu, Esra; Öz Orhan, Elif; Bayram, Özkan; Bilge Ocak, Sema
The purpose of this study is to determine the effects of gamma (γ)-ray irradiation on capacitance and conductance features of Al/Graphene/Al2O3/p-Si structure. Graphene has been grown on copper foil by the Chemical Vapor Deposition (CVD) method and transferred onto Al2O3/p-Si by the wet transfer method. After Al/Graphene/Al2O3/p-Si structure has been exposed to 30 kGy and 60 kGy γ-ray irradiation, capacitance, and conductance measurements have been accomplished at 300 K. Electrical parameters have been compared before and after γ-ray irradiation for 50 kHz and 500 kHz. These results have been confirmed that capacitance and conductance values have increased after γ-ray irradiation and, have decreased when the radiation dose was increased from 30 kGy to 60 kGy. It has been observed that series resistance has decreased after 30 kGy radiation dose and has increased with increasing radiation dose.
AtıfScopus13WoS12OpenAlex14İncele - MakaleAçık Erişim2021Scopus SJRQ1Extraction of Phenolic Compounds from Cornelian Cherry (Cornus mas L.) Using Microwave and Ohmic Heating Assisted Microwave Methods
Kutlu, Naciye; Isci, Asli; Sakiyan, Ozge; Yilmaz, Asim Egemen
In this study, it was aimed to extract bioactive compounds (phenolics and anthocyanins) from cornelian cherry (Cornus mas L.) using microwave (ME) and ohmic heating assisted microwave extraction (OH-ME) as an alternative to maceration (M). Total phenolic compound (TPC), total monomeric anthocyanin content (TMAC), antioxidant activity (AA), water-soluble solid matter (WSSM), color values, and pH of the extracts were determined. The effect of extraction time, solid to solvent ratio, microwave power, electrical field strength, and holding time during ohmic heating on extraction characteristics was investigated for different methods. Ohmic heating application prior to extraction has enhanced the TPC yield by 1.1 and 5.4-folds compared to that of ME and M, respectively. Moreover, the extraction time was decreased by approximately 42 and 95% as regards ME and M, respectively. The highest TMAC value (0.65 mg cya-3-glu/g dry matter) was observed with OH-ME. The experimental data obtained by ME and OH-ME methods was fitted to the Peleg model to describe the TPC yields. These results indicate that the combined application of ohmic heating and microwave extraction is a potential alternative method for total phenolic compounds extraction from cornelian cherry due to increased yields and reduced extraction times.
AtıfScopus48WoS40OpenAlex47İncele - MakaleAçık Erişim2021Scopus SJRQ1Assessment of Artificial Intelligence Models for Estimating Lengths of Gradually Varied Flow Profiles
Niazkar, Majid; Hajizadeh Mishi, Farshad; Eryilmaz Türkkan, Gökçen
The study of water surface profiles is beneficial to various applications in water resources management. In this study, two artificial intelligence (AI) models named the artificial neural network (ANN) and genetic programming (GP) were employed to estimate the length of six steady GVF profiles for the first time. The AI models were trained using a database consisting of 5154 dimensionless cases. A comparison was carried out to assess the performances of the AI techniques for estimating lengths of 330 GVF profiles in both mild and steep slopes in trapezoidal channels. The corresponding GVF lengths were also calculated by 1-step, 3-step, and 5-step direct step methods for comparison purposes. Based on six metrics used for the comparative analysis, GP and the ANN improve five out of six metrics computed by the 1-step direct step method for both mild and steep slopes. Moreover, GP enhanced GVF lengths estimated by the 3-step direct step method based on three out of six accuracy indices when the channel slope is higher and lower than the critical slope. Additionally, the performances of the AI techniques were also investigated depending on comparing the water depth of each case and the corresponding normal and critical grade lines. Furthermore, the results show that the more the number of subreaches considered in the direct method, the better the results will be achieved with the compensation of much more computational efforts. The achieved improvements can be used in further studies to improve modeling water surface profiles in channel networks and hydraulic structure designs.
AtıfScopus11WoS7OpenAlex12İncele - MakaleYalnız künye2021Scopus SJRQ1Production of lactose derivative hetero-oligosaccharides from whey by glucansucrase E81 and determination of prebiotic functions
İspirli, Hümeyra; Dertli, Enes
Bioactive oligosaccharides are important compounds for development of functional foods and ingredients. In this study, lactose derivative hetero-oligosaccharides were produced by acceptor reaction of glucansucrase E81 with whey. The synthesis of oligosaccharides was monitored by Thin Layer Chromatography (TLC) analysis followed by 1H and 13C Nuclear Magnetic Resonance (NMR) spectroscopy analysis which demonstrated the glycosylation of lactose with α-(1 → 2), α-(1 → 3) and α-(1 → 4) linkages. Liquid chromatography–mass spectrometry (LC-MS) analysis demonstrated the formation of DP 7 oligosaccharides from whey. The synthesized oligosaccharides were not digested under in vitro human gastric juice and α-amylase conditions. The prebiotic effect of lactose derivative hetero-oligosaccharides was tested and no growth in pathogenic strains was observed whereas certain probiotic strains utilised lactose derivative hetero-oligosaccharides as Carbon source and their growth was promoted. These findings can be important to reveal the potential of glucansucrases to produce functional oligosaccharides from different sources including waste materials.
AtıfScopus17WoS16OpenAlex16İncele - Derleme MakaleAçık Erişim2021Grammar teaching in the turkish language course curriculum: An examination in the context of acquisitions, activity, and teachers' opinions
Kodan, Hülya; Kara, Kürşad
This research aimed to reveal teachers' opinions about how the grammar-teaching process is related to the acquisitions in the curriculum, activities, and acquisitions presented in the textbooks teaching in mother tongue, the study reviewed different textbooks from four publishers, Cem, Sonuç, Koza, and Ministry of National Education (MEB) publications prepared for the 2018 primary school Turkish language course curriculum and Education Information Network (EBA) of the Turkish Ministry of Education. Moreover, opinions of ten primary school teachers who have taught all grades regarding the teaching process for grammar acquisition were investigated. The study conducted a case study method, which is one of the qualitative research techniques. Besides, a document analysis was conducted to obtain the research findings. Structured interview protocol and document review were used as the data collection tool. The findings of the study revealed that acquisition in the learning areas of reading and writing for grammar in the curriculum was not clearly and transparently identified, and the limits of the teaching framework were not specified. The study findings also revealed that information was transferred only in the majority of the grammar activities in the textbooks. Also, classroom teachers reported that they used different methods on the subjects they could embody in the teaching process, but they claimed to have difficulties in teaching abstract concepts.
AtıfScopus1OpenAlex1İncele - MakaleYayıncıda açık erişim2021Scopus SJRQ2Determination of flexural properties of hybrid composite using Cowper-Symonds rate-dependent material model
Erbayrak, Engin
This study addressed to determine the flexural properties of hybrid composite laminates (HCAFRE) under the strain rate sensitivity. The hybrid composite laminate was formed as consecutive stacking of a sequence of plain woven carbon fiber reinforced epoxy (CFRE) and a plain-woven aramid fiber reinforced epoxy (AFRE) laminates. The flexural tests were carried out at four different strain rates (0.01, 0.11, 0.55, 1.1 s−1) to determine the strain rate sensitivity of the HCAFRE. Moreover, the strain rate sensitivity of CFRE and AFRE was also determined individually. The effect of different fiber orientations (0°, 45°, and 90°) on the flexural properties of the composite laminates were also investigated at the scope of this study. In numerical analysis, composite laminates (CFRE, AFRE, and HCAFRE) were constituted in LS-DYNA finite element program using the Cowper-Symonds material model (MAT 112) which includes strain rate dependency. Consequently, it was seen that the experimental and numerical results were indicated a similar tendency to each other. Therefore, it was understood that the Cowper-Symonds material model is suited for the flexural behavior model of composite laminates under different strain rates.
AtıfScopus8WoS6OpenAlex8İncele - MakaleYalnız künye2021Scopus SJRQ2Determination of mechanical properties of polymer matrix composites reinforced with electrospinning N66, PAN, PVA and PVC nanofibers: A comparative study
Uslu, Emin; Gavgali, Mehmet; Erdal, Mehmet Okan; Yazman, Şakir; Gemi, Lokman
Fiber-reinforced polymer matrix composites are widely used in many structural applications thanks to their exceptional properties. In recent years, the use of electrospinning nanofibers with unique properties as reinforcement agents has attracted a great deal of attention in improving the performance of these composites. Although there are many promising studies on this subject in the literature, there are still many issues that need to be investigated. In this study, an experimental research reporting on the production and mechanical properties of two-phase polymer matrix composites reinforced with various types of thermoplastic nanofibers is presented. Nanofiber mats were produced from N66, PAN, PVA, and PVC polymers by electrospinning technique. Composites were obtained by embedding these nanofibers into epoxy resin by using vacuum infusion process. Mechanical properties of the composites were determined by performing tensile tests and the results were compared. The morphologies of nanofibers and the fracture surfaces of the composites were examined with SEM. Finally, statistical evaluations were carried out using mechanical data. According to tensile test results, the best ultimate tensile strength of 38.04 ± 3.7 MPa, elongation of 2.46 ± 0.4 % and toughness of 532 ± 137 kJ/m3 were obtained from N66 nanofiber composite, while PVA nanofiber composite was the most favorable in terms of Young's modulus (2.40 GPa). It was observed that the polymer type significantly affected the performance of the composite. In addition to the best mechanical properties, N66 composite was found to be more stable and reproducible than other specimens. Due to the good impregnation of nanofibers, it was conclusively determined that the use of vacuum infusion process is suitable for the production of these materials.
AtıfScopus79WoS73OpenAlex81İncele - MakaleAçık Erişim2021Scopus SJRQ3Virulence Factors, Antibiotic Resistance, And Antimicrobial Activity Of Enterococcus Spp. Isolated From Different Sources In Algeria
Houicher, Abderrahmane; Alkay, Zuhal; Bourahla, Mahdi; Dertli, Enes
This study aimed to isolate and identify different Enterococcus spp. from diverse sources including dromedary raw milk, rhizospheric soil and natural saline water samples and to determine their antimicrobial activities and safety aspects. From these sources, distinct strains of E. faecium, E. durans, E. hirae, and E. gallinarum species were detected. No virulence factors were observed for six Enterococcus strains while none of the tested Enterococci harboured the genes encoding cytolysin and aggregation substance. All tested strains showed a high sensitivity to many antibiotics, particularly vancomycin, and exhibited a remarkable antagonist activity toward Salmonella typhimurium, Fusarium graminearum and Penicillium expansum. PCR testing of enterocins revealed the co-presence of entA and entB among all tested Enterococci. No hemolytic reaction was also detected in Enterococci isolates, except for six strains. Based on these findings, potential candidates for use as biocontrol agents or probiotic starters were selected for further studies.
AtıfScopus4WoS3OpenAlex5İncele