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- MakaleYalnız künye2022Scopus SJRQ1Characterisation and functional roles of a highly branched dextran produced by a bee pollen isolate Leuconostoc mesenteroides BI-20
Yilmaz, Mustafa Tahsin; İspirli, Hümeyra; Taylan, Osman; Taşdemir, Volkan; Sagdic, Osman; Dertli, Enes
Lactic Acid Bacteria (LAB) from different niches can be responsible for the production of distinct exopolysaccharides (EPS) that might possess important structural and technological features. In this respect, the aim of this study was to isolate an EPS producer LAB strain from bee pollen environment. Leuconostoc mesenteroides BI-20 with a slimy-mucoid colony morphology was identified from bee pollen and the structural, technological and functional characteristics of EPS produced by this strain were determined. EPS BI-20 was a highly branched dextran containing 20% (1 → 3)-linked α-D-glucose branches determined by 1H and 13C NMR analysis. The presence of (1 → 6)/(1 → 3)-linked α-D-glucose linkages in dextran BI-20 was also confirmed by FTIR analysis. Dextran BI-20, with a molecular weight of 1 × 108 Da, possessed strong thermal properties, amorphous nature and highly branched and fibrous microstructural characteristics determined by DSC, TGA, XRD and SEM analysis, respectively. In terms of functional roles, dextran BI-20 demonstrated strong antioxidant capacity detected by ABTS and CUPRAC tests. Finally, no digestion was observed in dextran BI-20 under simulated gastric conditions. Results of this study unveiled techno-functional characteristics of dextran BI-20 produced by a bee pollen isolate LAB strain.
AtıfScopus39WoS36OpenAlex39
İncele - MakaleAçık Erişim2021Scopus SJRQ1Discrete sizing design of steel truss bridges through teaching-learning-based and biogeography-based optimization algorithms involving dynamic constraints
Artar, Musa; Carbas, Serdar
In this paper, Teaching-Learning Based Optimization (TLBO) and Biogeography-Based Optimization (BBO) algorithms are presented to examine the optimum discrete sizing design of steel truss steel bridges for minimizing the structural weights. Both proposed nature-inspired metaheuristic optimization algorithms are encoded in MATLAB with integration of a structural analysis program (SAP2000) via open application programming interface (OAPI). At the end, optimal steel profiles are selected from available discrete section lists by satisfying the structural restrictions, such as stress and displacement, involved by American Institute of Steel Construction-Allowable Stress Design (AISC-ASD). Additional to these, optimum discrete sizing design process is performed for the cases with and without dynamic constraints, which are adopted from natural periods of the bridge structures with respect to the mode shapes. The algorithmic performance of the proposed algorithms outperforms on both planar and spatial steel truss bridges. To prove this obtained optimal solutions are compared with previously reported optimum designs attaining via different metaheuristics. The final optimum discrete sizing designs of the steel truss bridges reveal that the proposed TLBO and BBO algorithms can easily be applied to discrete nonlinear programming problems.
AtıfScopus37WoS34OpenAlex37İncele - MakaleYalnız künye2021Scopus SJRQ1Exploring Self-Regulation Skills in the Context of Peer Assisted Writing: Primary School Students’ Sample
Sarikaya, İsmail; Yılar, Ömer
The purpose of this research is to determine the self-regulation behaviors demonstrated by the 4th grade students in the writing process within the scope of peer-assisted writing activities. The aims of this research include developing a measurement tool to identify the self-regulation behaviors exhibited by primary school students during the writing process. The study was designed in accordance with the qualitative research approach. The data were acquired through observation and video recordings. The study was carried out with 4th grade students in primary school and conducted in two stages as a pilot and main study. The pilot application was carried out with six students. The main study was carried out in two different 4th graders with 30 students. A cluster random sampling method was used to determine the research group. In order to determine the self-regulation behaviors demonstrated by students during the writing process, a semi-structured observation form was used. Expert opinions were taken for the validity and reliability of the created form. The data were subjected to descriptive and content analysis. As a result of the study, some self-regulation behaviors were determined that demonstrated by 4th grade students. These behaviors are presented under seven topics: regulation of environmental factors, regulation of sensory and motivational factors, planning, strategy development, regulation of temporal and social factors, monitoring, and evaluation.
AtıfScopus4WoS5OpenAlex8İncele - MakaleAçık Erişim2021Scopus SJRQ2Determination of pendulum hardness (KÖnig method) values against artificial weathering in water-based varnishes applied to some wood species after heat treatment (thermowood)
Ayata, Ümit; Çakicier, Nevzat
Scots pine, beech, and oak are the most important tree species in the furniture sector in Turkey. In this study, the aim is to determine pendulum hardness (König method) values against artificial aging in water-based varnishes applied to some wood species after heat treatment. For this purpose, Scots pine (Pinus sylvestris L.), sessile oak (Quercus petreae L.), and Eastern beech (Fagus orientalis L.) wood samples were heat-treated at 190 °C for 2 h and at 212 °C for 1–2 h according to the ThermoWood method. Later, one-and two-component water-based varnishes (WBVOne-Comp. and WBVTwo-Comp.) were applied to the material surfaces in accordance with the manufacturer’s recommendations for layer thickness for industrial applications. The materials were exposed to UV light using UV-A 340 nm fluorescent lamps for 144, 288, and 432 h in a QUV accelerated weathering tester. After these weathering periods, pendulum hardness values were determined. It was found that hardness values increased after weathering, and that WBVTwo-Comp. gave higher values than WBVOne-Comp..
AtıfScopus4WoS4OpenAlex3İncele - Kitap BölümüYalnız künye2021Covid-19 Impact on Global Supply Chains
Güleryüz, Didem
- MakaleYalnız künye2020Scopus SJRQ2A research on optimum designs of steel frames including soil effects or semi rigid supports using Jaya algorithm
Artar, Musa; Daloğlu, Ayşe T.
The effect of soil foundation plays active role in optimum design of steel space frames when included. However, its influence on design can be calculated after a long iterative procedure. So it requires longer computer time and more computational effort if it is done properly. The main purpose of this study is to investigate how these effects can be calculated in more practical way in a shorter time. The effects of semi-rigid column bases are taken into account in optimum design of steel space frames. This study is carried out by using JAYA algorithm which is a novel and practical method based on a single revision equation. The displacement, stress and geometric size constraints are considered in the optimum design. A computer program is coded in MATLAB to achieve corporation with SAP2000-OAPI (Open Application Programming Interface) for optimum solutions. Four different steel space frames including soil structure interaction taken from literature are investigated according to different semi-rigidly supported models depending on different rotational stiffness values. And the results obtained from analyses are compared with the results available in reference studies. The results of the study show that semi-rigidly supported systems in the range of appropriate rotational stiffness values offer practical solutions in a very short time. And close agreement is obtained with the studies on optimum design of steel space frames including soil effect underneath.
AtıfScopus8WoS9OpenAlex5İncele - MakaleYalnız künye2020Scopus SJRQ1Determination of magnetic levitation force properties of bulk MgB2 for different permanent magnetic guideways in different cooling heights
Savaskan, Burcu; Abdioglu, Murat; Ozturk, Kemal
In our study as different from the literature, the magnetic levitation force between a bulk MgB2 and two different permanent magnetic guideway (PMG) arrangements, which are Halbach and Conventional PMGs, were investigated in different cooling heights (CHs) and Field-Cooled (FC) condition at the temperatures of 37 K and 33 K. The cylindrical bulk MgB2 superconductor was fabricated by in-situ solid state reaction process with the diameter of 18 mm and the height of 5 mm. The XRD data indicates well developed MgB2 phase and the Jc value was obtained as 68 kA/cm2 at 30 K in the self-field. Experimental results show that MgB2 bulk above the Halbach PMG can exhibit better load capability at all the cooling heights between the bulk MgB2 and the PMG due to a more suitable magnetic field distribution. The maximum levitation force for Halbach PMG corresponds to 16.86 N whereas the conventional PMG shows 9.02 N at 37 K in cooling height of 77 mm. Additionally, the maximum levitation force increases while the CH increases because flux exclusion is more effective for larger CHs. It is considered that the experimental results obtained in study are very useful for future Maglev applications, because there are limited number of studies on magnetic levitation force of MgB2 bulk for different MgB2-PMG arrangements.
AtıfScopus17WoS14OpenAlex20İncele - EditoryalYalnız künye2019Preface
Akay, Ebru Çağlayan; Korkmaz, Özge
- MakaleAçık Erişim2020MACHINE LEARNING APPLICATION FOR OPTIMIZING ASYMMETRICAL REDUCTION OF ACETOPHENONE EMPLOYING COMPLETE CELL OF LACTOBACILLUS SENMAIZUKE AS AN ENVIRONMENTALLY FRIENDLY APPROACH
Taylan, Osman; Yilmaz, Mustafa Tahsin; Balubaid, Mohammed; Alamoudi, Rami; El-Obeid, Tahra; Dertli, Enes; Şahin, Engin; Bakhsh, Ahmed; Herrera-Viedma, Enrique
Recently, optimization of the bioreduction reactions by optimization methodologies has gained special interest as these reactions are affected by several extrinsic factors that should be optimized for higher yields. An important example for these kinds of reactions is the complete cell implications for the bioreduction of prochiral ketones in which the culture parameters play crucial roles. Such biocatalysts provide environmentally friendly and clean methodology to perform reactions under mild conditions with high conversion rates. In the present work, at the first step the Lactobacillus senmaizuke was isolated from sourdough and the complete cell application of Lactobacillus senmaizuke for the bioreduction of acetophenone was optimized by an Artificial Neural networks (ANNs) to achieve the highest enantiomeric excess (EE, %). The culture parameters, pH, temperature, incubation period and agitation speed were the experimental factors that were optimized to maximize EE (%) by machine learning algorithm of Artificial Intelligence modeling and the best conditions to maximize EE (95.5 %) were calculated to be pH of 5.7, temperature of 35 ºC, incubation period of 76 h and agitation speed of 240 rpm with very low sum of squared error value (0.611236 %) to bioreduce acetophenone using complete cell of Lactobacillus senmaizuke as a sourdough isolate GRAS microbial species. Accordingly, The ANN was employed to correctly establish the enantiomeric excess values of the specimen with an average absolute error 0.080739 %.
AtıfScopus3WoS2OpenAlex2İncele - MakaleYalnız künye2022Scopus SJRQ2Photocatalytic activity of cobalt aluminate nanoparticles synthesized by microwave-assisted combustion method
Karakaş, İbrahim Hakkı; Karcıoğlu Karakaş, Zeynep; Ertuğrul, Mehmet
Cobalt aluminate is one of the most widely-used spinel aluminate types. It is known that various structural, magnetic and morphological properties of spinel ceramics can vary depending on the synthesis technique and the starting chemicals used. In this study, initially, heat treatment was applied to cobalt aluminate nanoparticles synthesized by the microwave-assisted combustion method and the effects of the applied heat treatment on the structural properties were investigated. Characterization studies showed that cobalt aluminate spinel pigments were successfully synthesized. The optimum heat treatment temperature was determined as 700 °C. Then, the synthesized cobalt aluminate nanoparticles were used as photocatalysts for dye removal by photocatalytic oxidation from a synthetic wastewater containing Astrazon red textile dye and their photocatalytic activity was investigated at different catalyst dosages. Moreover, the same particles were also produced by conventional combustion technique. Then, their photocatalytic activities were studied and the data were compared with the results obtained from the experiments made with the samples produced with microwave assisted combustion method under the same experimental conditions. The results show that cobalt aluminate nanoparticles synthesized by microwave assisted combustion exhibit a better photocatalytic activity. In experiments performed with samples produced via microwave-assisted combustion method, all dyestuff content in the solution containing 50 mg/L dye was completely removed under UV irradiation for approximately 60 min. It was determined that the catalyst dosage had an effect on the reaction rate and the reaction was found to be compatible with the pseudo first order kinetic model.
AtıfScopus12WoS12OpenAlex13İncele - MakaleYalnız künye2022EVALUATING PROSPECTIVE ELEMENTARY SCHOOL TEACHERS’ WRITTEN AND ORAL ARGUMENTS ON ECOLOGY
Öztürk, Bilge; Okumuş, Seda
This study aimed to evaluate prospective elementary school teachers’ skills in creating written and oral arguments about the ecology. The case study method, one of the qualitative research approaches, was used. The study group consisted of 38 prospective elementary school teachers studying in the third year of an elementary teaching undergraduate program. As data collection tools, an expressions table containing ecology topics was designed by the researchers to evaluate the written argument creation skills of the participants and audio recordings of discussions were used to determine their oral argument creation skills. Descriptive analysis was used to analyze the data obtained in these ways. According to the findings of this research, the written and oral arguments of these prospective elementary school teachers were concentrated at a moderate level, but their oral arguments were at a higher level than their written arguments. It can be concluded that oral classroom discussions are more effective than written activities in creating arguments about the ecology.
- MakaleAçık Erişim2022Scopus SJRQ3Investigation of the recovery efficiency of CeUF method through RT-qPCR quantification of inactivated SARS-CoV-2 in untreated wastewater
Sait, Ahmet; Korkmaz, Serol; Parmaksiz, Ayse; Bayraktar, Bulent
Wastewater-based disease monitoring is an early warning system and a surveillance tool for infectious disease outbreaks regarding pathogens with pandemic potential. This study aimed at investigating the recovery efficiency of centrifugal ultrafiltration (CeUF), which is one of the most-used virus concentration methods, for inactive severe acute respiratory syndrome coronavi-rus 2 (SARS-CoV-2) added to wastewater. Inactivated SARS-CoV-2 was inoculated into untreated wastewater at different concentrations (4 × 103, 8 × 103, 16 × 103, 24 × 103 and 32 × 103 gene copy/ µL) and concentrated through ultrafiltration with a disposable centrifugal filter device. Total nucleic acids in concentrated filtrates were extracted and isolated by an automated system. In isolates, total RNA was measured by a UV/VIS spectrophotometer, and the recovered virus was quanti-fied by RT-qPCR with two gene regions (N1 and N2). The recovery rates were between 11% and 17.8% (mean 15.1%, CV below 15%). While there were positive correlations among the inoculated virus, total RNA and recovered virus, there was no correlation and linearity between the recovery rates. Despite limited recovery rates, CeUF integrated with RT-qPCR quantification can be a valid assay for monitoring SARS-CoV-2 in wastewater, and an early warning system.
AtıfScopus2WoS2OpenAlex3İncele - MakaleAçık Erişim2021Scopus SJRQ1The relationship between the mathematical reasoning skills and video game addiction of Turkish middle schools students: A serial mediator model
Öztürk, Mesut; Sarikaya, İsmail
The reasoning is required for important mathematical skills such as understanding mathematics, problem-solving, and proving. Therefore, it is crucial to examine the reasoning skills of individuals. This study was conducted to determine the serial mediator effect of the negative automatic thoughts and self-regulation within the relationship between reasoning skills and video game addiction of middle-school students. The correlational research model among the quantitative research designs was used in this study which was conducted with the participation of 468 middle-school students. Reasoning skill scale, video game addiction scale, negative automatic thoughts scale, and perceived self-regulation scale were used in the data collection process. The obtained data were analyzed with correlation analysis and mediator variable analysis. In the end, the results indicated that negative automatic thoughts and self-regulation skills had a mediator effect between middle-school students’ video game addiction and reasoning skills.
AtıfScopus16WoS9OpenAlex20İncele - MakaleAçık Erişim2019Scopus SJRQ3Production of enantiomerically pure (S)-phenyl(pyridin-2-yl)methanol with Lactobacillus paracasei BD101
Şahin, Engin; Serencam, Hüseyin; Dertli, Enes
Asymmetric reduction studies of heteroaryl ketones, including phenyl(pyridin-2-yl)methanone in enantioselective form with biocatalysts are very few, and chiral heteroaryl alcohols have been synthesized generally in the small scale. In this study, seven bacterial strains have been used to produce the (S)-phenyl(pyridin-2-yl)methanol in high enantiomeric excess and yield. Among the tested strains, Lactobacillus paracasei BD101, was found to be the best biocatalyst for the reducing phenyl(pyridin-2-yl)methanone to the (S)-phenyl(pyridin-2-yl)methanol at gram scale. The asymmetric bioreduction conditions were systematically optimized using L. paracasei BD101, which demonstrated excellent enantioselectivity and high level of conversion for the bioreduction reaction. (S)-phenyl(pyridin-2-yl)methanol, which is an analgesic, was produced enantiomerically pure form in the first time on gram scale using a biocatalyst. In total, 5.857 g of (S)-phenyl(pyridin-2-yl)methanol in enantiomerically pure form (>99% enantiomeric excess) was obtained in 52 h with 93% yield using whole cells of L. paracasei BD101. Enantiomerically pure (S)-phenyl (pyridin-2-yl)methanol, which is an analgesic, was first produced in the gram scale using a biocatalyst with excellent ee (>99%) and yield (93%).
AtıfScopus9WoS7OpenAlex9İncele - MakaleAçık Erişim2022Scopus SJRQ3Comparative Analysis of Migrant Integration Policies of Türkiye and Selected European Countries; [Türkiye ve Seçilmiş Avrupa Ülkelerinin Göçmen Entegrasyon Politikalarının Karşılaştırmalı Olarak İncelenmesi]
Ustabulut, Mete Yusuf; Boylu, Emrah; Başar, Umut
Türkiye’s migrant integration policy, which is one of the most migration-receiving countries in the Middle East owing to regional conflicts during the 2000s, is assessed alongside that of other receiving nations in the “Migrant Integration Policy Index” (MIPEX). These index ranks nations in eight key categories: labor market mobility, family reunion, education, health, political participation, permanent residence, access to nationality, and anti-discrimination. This study examines Türkiye’s change in migration policy ratings by comparing the index 2015 and 2020 with six European countries (Germany, Belgium, France, Norway, Finland, Sweden). It is found that there was a significant disparity in index scores between Türkiye and these European countries in the 2015 MIPEX report; however, this difference has narrowed in the 2020 report. Türkiye’s migrant integration policy rankings have improved substantially (+17), according to the 2020 report. As a result, Türkiye’s policy indicator has increased from “slightly unfavourable” to “halfway favourable”. Although this score and increase are not at the desired level, they may indicate comprehensive improvements in Türkiye’s integration policies in the following report.
AtıfOpenAlex2TR Dizin3
İncele - MakaleAçık Erişim2022Scopus SJRQ1Assessment of Climate Change Impact on Discharge of the Lakhmass Catchment (Northwest Tunisia)
Ben Nsir, Siwar; Jomaa, Seifeddine; Yıldırım, Ümit; Zhou, Xiangqian; D’Oria, Marco; Rode, Michael; Khlifi, Slaheddine
The Mediterranean region is increasingly recognized as a climate change hotspot but is highly underrepresented in hydrological climate change studies. This study aims to investigate the climate change effects on the hydrology of Lakhmass catchment in Tunisia. Lakhmass catchment is a part of the Medium Valley of Medjerda in northwestern Tunisia that drains an area of 126 km². First, the Hydrologiska Byråns Vattenbalansavdelning light (HBV-light) model was calibrated and validated successfully at a daily time step to simulate discharge during the 1981–1986 period. The Nash Sutcliffe Efficiency and Percent bias (NSE, PBIAS) were (0.80, +2.0%) and (0.53, −9.5%) for calibration (September 1982–August 1984) and validation (September 1984–August 1986) periods, respectively. Second, HBV-light model was considered as a predictive tool to simulate discharge in a baseline period (1981–2009) and future projections using data (precipitation and temperature) from thirteen combinations of General Circulation Models (GCMs) and Regional Climatic Models (RCMs). We used two trajectories of Representative Concentration Pathways, RCP4.5 and RCP8.5, suggested by the Intergovernmental Panel on Climate Change (IPCC). Each RCP is divided into three projection periods: near-term (2010–2039), mid-term (2040–2069) and long-term (2070–2099). For both scenarios, a decrease in precipitation and discharge will be expected with an increase in air temperature and a reduction in precipitation with almost 5% for every +1 °C of global warming. By long-term (2070–2099) projection period, results suggested an increase in temperature with about 2.7 °C and 4 °C, and a decrease in precipitation of approximately 7.5% and 15% under RCP4.5 and RCP8.5, respectively. This will likely result in a reduction of discharge of 12.5% and 36.6% under RCP4.5 and RCP8.5, respectively. This situation calls for early climate change adaptation measures under a participatory approach, including multiple stakeholders and water users.
AtıfScopus11WoS11OpenAlex14İncele - MakaleAçık Erişim2019Scopus SJRQ1Response surface optimization for a nonlinearly constrained irregular experimental design space
Ozdemir, Akin; Cho, Byung Rae
Finding optimum conditions for process factors in an engineering optimization problem with response surface functions requires structured data collection using experimental design. When the experimental design space is constrained owing to external factors, its design space may form an asymmetrical and irregular shape and thus standard experimental design methods become ineffective. Computer-generated optimal designs, such as D-optimal designs, provide alternatives. While several iterative exchange algorithms for D-optimal designs are available for a linearly constrained irregular design space, it has not been clearly understood how D-optimal design points need to be generated when the design space is nonlinearly constrained and how response surface models are optimized. This article proposes an algorithm for generating the D-optimal design points that satisfy both feasibility and optimality conditions by using piecewise linear functions on the design space. The D-optimality-based response surface design models are proposed and optimization procedures are then analysed.
AtıfScopus18WoS13OpenAlex16İncele - MakaleAçık Erişim2022Scopus SJRQ2Existence and multiplicity of solutions for p(.)-Kirchhoff-type equations
Ayazoğlu, Rabil; Akbulut, Sezgin; Akkoyunlu, Ebubekir
This paper is concerned with the existence and multiplicity of solutions of a Dirichlet problem for p(.) - Kirchhoff-type equation (Formula Presented). Using the mountain pass theorem, fountain theorem, dual fountain theorem and the theory of the variable exponent Sobolev spaces, under appropriate assumptions on f and M, we obtain results on existence and multiplicity of solutions
AtıfScopus9WoS9OpenAlex9İncele - MakaleAçık Erişim2020Scopus SJRQ2Calorific power improvement of wood by heat treatment and its relation to chemical composition
Domingos, Idalina; Ayata, Umit; Ferreira, José; Cruz-Lopes, Luisa; Sen, Ali; Sahin, Sirri; Esteves, Bruno
Chemical composition influences the calorific power of wood, mainly due to the calorific power of structural compounds and extractives. Heat treatment changes the chemical composition of treated wood. This work studies the relationship between chemical composition and calorific power improvement by heat treatment. Samples were heat-treated by the ThermoWood process ® for 1 h and 2 h. High heating value (HHV) and chemical composition; lignin, cellulose, hemicelluloses and extractives in dichloromethane, ethanol, and water were determined. The HHV of untreated wood ranged between 18.54-19.92 MJ/kg and increased with heat treatment for all the tested species. A positive linear correlation was found between HHV and Klason lignin (R2 = 0.60). A negative trend was observed for holocellulose, cellulose, and hemicelluloses content against HHV, but with low determination coefficients for linear regression. The best adjust for polysaccharides was found for hemicelluloses content. A positive correlation could be found for dichloromethane extractives (R2 = 0.04). The same was obtained in relation to ethanol extractives with R2 = 0.20. For water and total extractives, no clear positive or negative trends could be achieved. The results showed that the HHV of wood increased with heat treatment and that this increase was mainly due to the increase in lignin content.
AtıfScopus32WoS27OpenAlex38İncele - MakaleAçık Erişim2022Scopus SJRQ1Easy-to-Implement Ultra-Thin, Wide-Band, and Multi-Functional Polarization Converter for K and Ka Band Applications
Coskun, Aykut; Hasar, Ugur Cem; Ozmen, Ahmet; Ertugrul, Mehmet
This article presents an ultrathin, broadband, and multipurpose polarization converter design utilizing an anisotropic metasurface for K and Ka band. The proposed polarization converter, which has a single layer F4B as a substrate material with hexagonal-shaped metallic solid structure along with hexagonal ring with diagonal splits on its front surface and a background (a completely metallic surface) on its back, works as not only a circular polarization converter but also a linear polarization to circular polarization (LP to CP) converter. Its polarization conversion rate (PCR) is more than 90% in the frequency range from 17.87 to 43.15 GHz, covering all of the K and Ka bands with a relative bandwidth of 83% under normal incidence case. For incidence angles up to 40°, PCR is observed to be greater than 75% in almost all of the K and Ka bands (except for the frequency range between 24.72 and 27.11 GHz). Furthermore, the proposed design has LP to CP in two different frequency bands, 16.23–16.74 GHz and 48.6–48.8 GHz. The proposed polarization converter, as advantages, is low cost, ultra thin, broadband, and facile, which can be useful in linear cross polarization conversion in K and Ka band applications.
AtıfScopus10WoS9OpenAlex10İncele
