Sürdürülebilir Kalkınma Amaçları
Yazarlar
- Dertli, Enes(115)
- Kaya, Yunus(50)
- Ayata, Ümit(48)
- Şahin, Engin(48)
- İspirli, Hümeyra(46)
- Bayraktar, Bülent(42)
- Şenay, Volkan(41)
- Can, Zehra(39)
- Özen, Soner(37)
- Bayram, Sinan(35)
- Pat, Suat(35)
- Öztürk, Mesut(35)
- Ecem Bayram, Nesrin(34)
- Esmer, Yusuf(34)
- Battal, Fetullah(33)
- Artar, Musa(32)
- Öner, Erdal(32)
- Korkmaz, Şadan(31)
- Yilmaz, Mustafa Tahsin(31)
- Ertugrul, Mehmet(30)
- Mercan, Emin(30)
- Hasar, Ugur Cem(29)
- Kutlu, Naciye(28)
- Özdemir, Akın(27)
- Kul, Murat(26)
- Cuce, Erdem(25)
- Kamiloğlu, Aybike(25)
- Bayram, Ozkan(24)
- Sefali, Abdurrahman(24)
- Sert, Durmuş(24)
- Çolak, Murat(24)
- Ayazoglu, Rabil(22)
- Gıdık, Betül(22)
- Maden, Sedat(22)
- Ustabulut, Mete Yusuf(22)
- Uçurum, Metin(22)
- Akeren, Zahide(21)
- Dirican, Ebubekir(21)
- Kara, Yakup(21)
- Abdioglu, Murat(20)
Yayınlar
- MakaleYalnız künye2022Scopus SJRQ1Nondestructive Experimental Measurement, Model Updating, and Fatigue Life Assessment of carsamba Suspension Bridge
Günaydin, Murat; Sunca, Fezayil; Altunisik, Ahmet Can; Ergün, Mustafa; Okur, Fatih Yesevi
This paper includes the structural condition assessment of a 164-m suspension bridge in accordance with numerical and experimental methods. A finite-element model was developed using SAP2000 software so that the assessment of the bridge could be calculated numerically. The operational modal analysis method was also used to obtain experimental dynamic characteristics. In this context: (i) numerical dynamic characteristics of the bridge were obtained and compared with the experimental dynamic characteristics, (ii) a model updating procedure was carried out to minimize the differences between the numerical and experimental natural frequencies, (iii) static and dynamic analyses of the bridge were carried out by using the initial and updated finite-element models, (iv) fatigue life assessment of the bridge was investigated, and (v) the utility of the bridge for pedestrians and vehicles was checked according to various regulations. The results showed that updating the finite-element model had a significant role to play in the static and dynamic behavior of the bridge. The results also demonstrated that the bridge was designed to be extremely safe against static, dynamic, and fatigue loads. Finally, it was concluded that the bridge investigated behaves as a girder bridge rather than a suspension bridge.
AtıfWoS17OpenAlex18
İncele - MakaleAçık Erişim2022Scopus SJRQ1Structural Investigation of Masonry Arch Bridges Using Various Nonlinear Finite-Element Models
Tapkin, Serkan; Tercan, Emre; Motsa, Siphesihle Mpho; Drosopoulos, Georgios; Stavroulaki, Maria; Maravelakis, Emmanuel; Stavroulakis, Georgios
This article presents an investigation of the structural behavior of a masonry arch bridge in Turkey. An analytical study has been conducted to provide the geometry of the structure, using laser scanning. A point cloud describing the geometry was obtained and properly transformed into a format that is appropriate for structural analysis software (CAE). Then, nonlinear finite-element models were developed to simulate structural responses of the bridge. The goal of the article is to highlight the influence of both continuum and discrete approaches and related constitutive laws on the responses of the bridge. Thus, continuum damage laws and a discrete model consisting of unilateral contact-friction interfaces were developed. Different load cases were tested and a comparison between the results obtained from the different approaches was considered. The failure mechanisms and the ultimate strengths were derived, and core points of the models were highlighted. The output of this work shows how the different failure models predict the behavior of the masonry arches. It also shows that the three-hinge mechanism, which has been depicted in classical studies for single-span arch masonry bridges under a horizontal settlement of supports, may also be obtained for multiarch bridges. Similarly, downward, vertical settlement of supports may result in the development of two hinges, as in single-span arches. Finally, the beneficial influence of the backfill in limiting the failure in the arch is addressed.
AtıfWoS18OpenAlex21İncele - MakaleAçık Erişim2022Scopus SJRQ1Screening of plant pollen sources, polyphenolic compounds, fatty acids and antioxidant/antimicrobial activity from bee pollen
Gercek, Yusuf Can; Celik, Saffet; Bayram, And Sinan
In this study, the botanical origin, total flavonoid and phenolic content, antioxidant activity, phenolic profile and fatty acid composition of mixed bee pollen loads collected in Bayburt, Turkey, were determined. In addition to these assays, antibacterial activity of bee-collected pollen extract (BCPE) against a variety of food-borne pathogenic bacteria was determined in vitro. Pollen loads were classified into five botanical families based on their color: Asteraceae, Fabaceae, Campanulaceae, Cistaceae and Rosaceae. Total flavonoid, total phenolic, CUPRAC and CERAC concentrations were 173.52 mg GAE/g, 79.21 mg QE/g, 85.59 mg Trolox/g and 118.13 mg Trolox/g, respectively. Twenty-three phenolic compounds were scanned in bee pollen extract by LC-MS/MS, with rutin being the most abundant. Cis-4,7,10,13,16,19 docosahexaenoic acid was the predominant fatty acid, followed by cis-11-eicosenoic acid, palmitic acid, and alfa linolenic acid. In addition, the agar well diffusion (AWD) and micro-broth dilution methods were used to determine of the antibacterial activity of the BCPE sample. MIC values were observed to vary between 2.5–5 mg/mL for Gram-positive bacteria and 5–10 mg/mL for Gram-negative bacteria. These findings indicate that bee pollen could be a potential source of antioxidants and antimicrobials.
AtıfScopus62WoS56OpenAlex71
İncele - MakaleAçık Erişim2022Scopus SJRQ2Investigation of inlet air pressure and evaporative cooling of four different cogeneration cycles
Karaali, Rabi
The objective of this study was to search the effects of the inlet air compressor pressure and evaporative cooling of four different cogeneration plants that are absorption cooling (ab), basic (bsc), air heating (airh), and air fuel heating (airfh) cogeneration systems by using the first law and the second law of thermodynamics, and the exergy analysis methods. For analysis, a program is written by the author in the FORTRAN programming language. Decreasing the atmospheric pressure or increasing the installation altitude of the plants increases the Z factor (ratio of lost exergy to useful exergy) of the four cycles about 10-13%. Also, decreasing inlet air pressure decreases the specific work about 25-28%, and the fuel energy saving ratio of the four cycles decreases about 29-30%. The method of water spray cooling of the compressor inlet air especially in the summer months, the humidity increases and the evaporative cooling can be obtained. By using this method, the ratio of lost exergy to useful exergy can be decreased for the four cycles about 0.5-2%. Also, the specific work of the four cycles can be increased about 1.2-6%.
AtıfOpenAlex4İncele - MakaleAçık Erişim2022Scopus SJRQ2Investigations of low-velocity impact behaviour of single-lap joints having dissimilar hybrid composite adherends through cohesive zone model approach
Erbayrak, Engin
The low-velocity impact behavior of single-lap joints was investigated in this study. In single-lap joints, woven carbon fiber reinforced epoxy (CFRE) and plain woven glass fiber reinforced epoxy (GFRE) laminates as well as a hybrid composite laminate (HCGFRE), which is formed by stacking carbon and glass composite laminates, are used as adherends. Araldite 2011 and Araldite 138 M/HV998 epoxy adhesives were used with different mechanical properties for joining similar and dissimilar composite adherends. Low-velocity impact tests were carried out with 40 J impact energy. Reaction force-time and impact energy-time graphs were obtained from the experimental study as impact response. In numerical analyses, the damage approach of composite adherend was modeled using composite stress-based failure model (Mat 59) and adhesives were modeled utilizing a mixed-mode cohesive zone model (Mat 138) that existed in LS-DYNA explicit finite element software. It was seen that the numerical results indicated a similar tendency with the experimental results due to the modeling of the adhesives using the proper cohesive zone model, the application of correct boundary conditions, and the selection of the correct contact type.
AtıfScopus9WoS9OpenAlex10İncele - MakaleAçık Erişim2022Scopus SJRQ2EXTRACTIVES IN THERMALLY MODIFIED TROPICAL HARDWOODS
Esteves, Bruno; Ayata, Umit; Cruz-Lopes, Luísa; Brás, Isabel; Ferreira, José; Domingos, Idalina
Chemical composition of wood is known to change during thermal treatments. Two species grown in Turkey, afrormosia (Pericopsis elata) and duka (Tapirira guianensis) were heat treated according to Thermowood® method. Lignin, cellulose, hemicelluloses and extractives in dichloromethane, ethanol and water were determined. Wood extracts were analysed by gas chromatography with mass detection and existing compounds were identified by NIST17 database. Results show that hemicelluloses and cellulose content decreased for both heat-treated woods along the treatment while lignin percentage increased. The analysis of extractives has shown several compounds normally associated to lignin thermal degradation that increased along the treatment. At the same time several compounds associated to carbohydrate thermal degradation were found in all the extracts for both heat-treated woods. These founding have allowed the understanding of the degradation pattern of wood during thermal modification. There was not much difference between afrormosia and duka woods structural compounds behaviour along thermal modification. However, the variation of the amount of extractives along the treatment depended on the species.
AtıfScopus20WoS20OpenAlex16İncele - MakaleAçık Erişim2022Scopus SJRQ4Some Physical, Biological, Hardness, and Color Properties of Wood Impregnated with Propolis
Akçay, Çağlar; Ayata, Ümit; Birinci, Emre; Yalçın, Mesut; Kolaylı, Sevgi
Propolis is a bee product collected by honeybees from various tree species in nature. It has antifungal, antibacterial, antioxidant, and anticancerogenic properties. Recently, propolis has been used in wood protection area because it has antifungal properties and is a natural and environmentally friendly material. In this study, some deciduous wood species were treated with methanolic propolis extracts. Propolis solutions were prepared by dissolving propolis in methanol in concentrations of 0.5%, 2.5%, 5%, and 8%. These solutions were forced deep into the Scots pine (Pinus sylvestris L.), fir (Abies nordmanniana), and spruce (Picea orientalis L.) woodblocks under vacuum and pressure. Water uptake and water-repellent efficiencies of the woodblocks were tested at 2-, 4-, and 20-hour immersion periods. Sample blocks were tested against wood-destroying house borer (Hylotrupes bajulus) (Coleoptera, Cerambycidae) larvae for 21 weeks. In addition, color changes of woodblocks treated with propolis were determined. According to results obtained in the study, the highest water-repellent efficiency was 61.4% in propolis-impregnated spruce wood at concentration level of 8% during the 2-hour period. These results show that propolis extracts could be used as hydrophobic material for wood. Larvae mortality rates indicated that 8% concentration level was not adequate to overcome H. bajulus larvae or propolis is not effective against H. bajulus larvae. While L* value decreases with the increase of impregnation rate, a* and b* values increase in all wood types. As the impregnation rate increased, the total color difference also increased.
AtıfScopus2WoS2TR Dizin1
İncele - MakaleAçık Erişim2022Scopus SJRQ2Efficient bioreduction of cyclohexyl phenyl ketone by Leuconostoc pseudomesenteroides N13 biocatalyst using a distance-based design-focused optimization model
Özdemir, Akın; Şahin, Engin
Whole-cell biocatalysts have been a popular method for the preparation of chiral alcohols. Although asymmetric reduction of cyclohexyl(phenyl)methanone (1) by chemical catalysts is common, a biocatalytic asymmetric reduction is extremely rare. In this respect, we report herein that Leuconostoc pseudomesenteroides N13 was successfully employed as a biocatalyst to reduce 1 to (S)-cyclohexyl(phenyl)methanol ((S)-2). Furthermore, the use of a mathematical optimization strategy for asymmetric reduction of substrate 1 is not known in the current literature. The new distance-based design-focused optimization model was used to enhance the conversion of the substrate, enantiomeric excess (ee) of product, and yield. The distance-based design-focused optimization model identified the following optimal bioreduction conditions: pH=6.46, temperature=30°C, incubation period=72 hours, and agitation speed=199 rpm. Then it was stated that under these ideal conditions, (S)-2 may be produced with 99 % ee and 98.46 % conversion rate (cr). (S)-2 was achieved with 99% ee, and 99% cr as a consequence of the experimental reaction carried out under the indicated optimization conditions. It has been shown that Leuconostoc pseudomesenteroides N13 can be utilized as a biocatalyst in asymmetric reduction reactions. This study, in addition to being the first example of a bioreduction of substrate 1 by mathematical optimization, also demonstrates for the first time the distance-based design-focused model can be used in the bioreduction reaction.
AtıfScopus9WoS9OpenAlex8İncele - MakaleAçık Erişim2022Scopus SJRQ1Comparative seismic design optimization of spatial steel dome structures through three recent metaheuristic algorithms
Carbas, Serdar; Artar, Musa
Steel dome structures, with their striking structural forms, take a place among the impressive and aesthetic load bearing systems featuring large internal spaces without internal columns. In this paper, the seismic design optimization of spatial steel dome structures is achieved through three recent metaheuristic algorithms that are water strider (WS), grey wolf (GW), and brain storm optimization (BSO). The structural elements of the domes are treated as design variables collected in member groups. The structural stress and stability limitations are enforced by ASD-AISC provisions. Also, the displacement restrictions are considered in design procedure. The metaheuristic algorithms are encoded in MATLAB interacting with SAP2000 for gathering structural reactions through open application programming interface (OAPI). The optimum spatial steel dome designs achieved by proposed WS, GW, and BSO algorithms are compared with respect to solution accuracy, convergence rates, and reliability, utilizing three real-size design examples for considering both the previously reported optimum design results obtained by classical metaheuristic algorithms and a gradient descent-based hyperband optimization (HBO) algorithm.
AtıfScopus15WoS13OpenAlex15İncele - MakaleYayıncıda açık erişim2022Scopus SJRQ3Thiol disulfide homeostasis in primary dysmenorrhea
Savrun, Atakan; Savrun, Şeyda Tuba; Dirican, Ebubekir; Gökçen, Emre; Arıcı, Yeliz Kasko; Aygün, Ali; Korkmaz, Vakkas; Neşelioğlu, Salim; Erel, Özcan; Kıran, Tuğba Raika
Oxidative stress is defined as a result of the loss of balance between the production of free radical or reactive oxygen species and the antioxidant system. This study aimed to determine the level of thiol-disulfide homeostasis (TDH) in the serum of women with primary dysmenorrhea. The study group consisted of 42 subjects with primary dysmenorrhea, and the control group consisted of 30 volunteer women with demographic characteristics similar to the study group. Native thiol (SH), total thiol (TSH), disulphide (SS), and SH/SS parameters were measured for TDH of the subjects. The SH (p = 0.038) and SH/TSH (p = 0.046) levels were significantly higher while SS (p = 0.013), SS/SH (p = 0.042) and SS/TSH (p = 0.046) levels were lower in the study group than in the healthy control group. The SS cut-off value was determined as 17.85 in the study group (sensitivity = 61.9%, specificity = 43.3%). Therefore, the probability of dysmenorrhea may increase significantly when SS levels fall below this value. In subjects with dysmenorrhea, there was a decrease in SS levels and an increase in SH levels in order to protect the cells and tissues from the harmful effects of free radicals.
AtıfOpenAlex1İncele - MakaleAçık Erişim2022Scopus SJRQ1Conventional and Microcellular Injection Molding of a Highly Filled Polycarbonate Composite with Glass Fibers and Carbon Black
Yilmaz, Galip; Devahastin, Apichart; Turng, Lih-Sheng
Conventional solid injection molding (CIM) and microcellular injection molding (MIM) of a highly filled polycarbonate (PC) composite with glass fibers and carbon black were performed for molding ASTM tensile test bars and a box-shape part with variable wall thickness. A scanning electron microscope (SEM) was used to examine the microstructure at the fractured surface of the tensile test bar samples. The fine and uniform cellular structure suggests that the PC composite is a suitable material for foaming applications. Standard tensile tests showed that, while the ultimate strength and elongation at break were lower for the foamed test bars at 4.0–11.4% weight reduction, their specific Young’s modulus was comparable to that of their solid counterparts. A melt flow and transition model was proposed to explain the unique, irregular “tiger-stripes” exhibited on the surface of solid test bars. Increasing the supercritical fluid (SCF) dosage and weight reduction of foamed samples resulted in swirl marks on the part surface, making the tiger-stripes less noticeable. Finally, it was found that an injection pressure reduction of 25.8% could be achieved with MIM for molding a complex box-shaped part in a consistent and reliable fashion.
AtıfScopus2WoS2OpenAlex3İncele - MakaleAçık Erişim2022Scopus SJRQ4Angle Conceptions of Students with Learning Disabilities and Hearing Impairments; [Öğrenme Güçlüğüne Sahip ve İşitme Engelli Öğrencilerin Açı Kavrayışları]
Güven Akdeniz, Dilşad; Gürefe, Nejla; Arikan, Ahmet
The angle concept is central to the development of geometry knowledge, which is important and functional for everyday life. In this context, the aim of this study was to examine the understanding of the angle concept of middle school students with learning disabilities (LDs) and hearing impairment (HI). The participants of this study, which was a case study, were identified with the criterion and convenience sampling methods. The participants were two students, one of whom with LDs and the other had a HI, each of whom was in grade 6. Data collected through individual clinical interviews with the students were analyzed using the cross-case analysis method. According to the findings of the study, the angle conception of both students was limited to the shape of the angle, and both students were aware of the concept of direction in the angle, but the student with the LD perceived the angle more statically, and did not have enough knowledge about the angle measurement or its unit. It was seen that the student with the HI confused the angle and angle measure, but was aware of the various angles according to their measures.
AtıfScopus2WoS1OpenAlex2İncele - MakaleAçık Erişim2022Scopus SJRQ4The effect of carvacrol on oxido-inflammatory ovarian injury and infertility induced by ischemia-reperfusion in rats
Sahin, Nurullah; Delibas, Ilhan Bahri; Isaoglu, Unal; Suleyman, Bahadir; Yazici, Gulce Naz; Coban, Taha Abdulkadir; Uzel, Kemine; Suleyman, Halis; Arslan, Veysel
Background: Increased oxidants and proinflammatory cytokines play a role in the pathogenesis of ovarian ischemia-reperfusion (OIR) injury and related infertility. Carvacrol has antioxidant, antibacterial and anti-inflammatory properties. Methods: Protective effect of carvacrol against ischemia-reperfusion (IR)-related ovarian damage and infertility was investigated. IR process were applied to the ovaries of rats, which were divided into the following groups (n = 12): OIR, IR +50 mg/kg carvacrol (IRC-50), IR +100 mg/kg carvacrol (IRC-100) and sham group (SG). After the reperfusion process, six rats from each group were killed and the removed ovaries were examined biochemically and histopathologically. The remaining animals were kept two months with mature male rats to reproduce. Results: At a dose of 50 mg/kg, carvacrol suppressed the oxidant parameter increase and antioxidant decrease caused by IR in ovarian tissue. At a dose of 100 mg/kg, carvacrol antagonized both oxidant and proinflammatory cytokine increase and antioxidant decrease. Histopathologically, severe degeneration of follicles in the ovaries of the OIR group, necrotic cell accumulations, hemorrhage in the corpus luteum, edema in the interstitial tissue, polymorphous nuclear leukocyte (PNL) infiltration, and congestion and dilation of blood vessels were detected. Inflammatory symptoms such as edema in the ovarian tissue, congested dilated blood vessels and PNL infiltration were observed at a dose of 50 mg/kg of carvacrol, but these histopathological findings were not observed at a dose of 100 mg/kg. Conclusion: A dose of 100 mg/kg carvacrol, which eliminated inflammatory damage, significantly prevented the development of IR-induced infertility. Carvacrol may be beneficial in the treatment of IR-related ovarian damage and infertility. Copyright:
AtıfScopus2WoS1OpenAlex2İncele - MakaleAçık Erişim2022Zero in arithmetic operations: A comparison of students with and without learning disabilities
Akdeniz, Dilşad Güven; Topbaş, Esra Selcen Yakıcı; Argün, Ziya
The aim in the current study is to examine the conceptualizations of zero in arithmetic operations among students with learning disabilities (LD) and no learning disabilities (N-LD). The similarities and differences in the understandings of students with LD and N-LD of zero in arithmetical operations will be discussed. The study is a multiple case study with a qualitative research design. Six students, 3 students with LD and 3 with N-LD aged between 10 and 12 years participated in the study. The data were collected through clinical interviews. The data were analyzed by content analysis. Students‘ limited understanding of zero and operations affects their interpretation of arithmetic operations with zero. The conceptualizations of students with LD and N-LD regarding specifically division by zero show similarities with the exception of their use of the knowledge about operations. It has been observed that LD students have developed a different algorithm when it comes to addition and multiplication with zero. Through this study examining the differences in the understandings of students with LD and N-LD on a specific concept in terms of underlying conceptions, it is thought to provide an insight in terms of discovering LD and a more detailed recognition of these students' mathematics.
AtıfScopus2OpenAlex1İncele - MakaleAçık Erişim2022Scopus SJRQ2Comparison of classical and newly designed motion profiles for motion-based control of flexible composite manipulator
Uyar, M.
The motion profiles defined to move the robot manipulators directly affect the endpoint position accuracy, position repeatability, and vibration control of the manipulators in engineering applications, especially in flexible manipulators. This study deals theoretically and experimentally with the dynamic performance of two different motion profiles in reducing the vibration amplitudes of a single-link flexible composite manipulator. Manipulator is produced from epoxy-glass composite material with a layer orientation of [0/90/0/0/90/0] lay-up. For theoretical studies, the SimMechanics-based flexible dynamic model is created using flexible beam block in MATLAB/Simulink, and the finite element model is established with a layered structural solid element in ANSYS. Two different motion profiles are defined to drive the manipulator for different stopping positions and motion times. Simulations are achieved by using motion profiles. The performance of the motion profiles is evaluated by considering the reduction ratio of residual displacement and acceleration vibrations generated at the endpoint of the manipulator. RMS values of residual vibrations are calculated to determine the rate of residual vibration suppression. Reduction ratios are determined by considering the maximum vibration amplitudes as the reference RMS value. The effectiveness of the motion profiles is presented in comparison with the reduction rates. Simulation results obtained using both displacement and acceleration vibration responses are verified with experiments for all motion cases. Also, the modeling and analysis of the composite manipulator are verified by simulations and experiments with the SimMechanics-based modeling method, and the reliability of the proposed method is increased.
AtıfScopus8WoS8OpenAlex8İncele - MakaleYalnız künye2022Scopus SJRQ1Production and characterisation of goat milk powder made from sonicated whole milk concentrates
Sert, Durmuş; Mercan, Emin
In the present study, goat milk powder (GMP) was produced from sonicated whole milk concentrates for 0–60 min. The physicochemical, functional, and microbiological properties and powder flow behaviours of the GMP samples were determined. Sonication decreased firmness and consistency values of milk concentrate with the increased treatment time. L∗ value of the sonicated GMPs was higher than that of the control. The bulk density of samples was between 0.681 and 0.736 g cm−3, increased by sonication. However, sonication resulted in lower wettability, dispersibility, and foaming capacity. The D [3,2] value of GMPs ranged from 21.9 to 31.1 μm, increased by sonication. Sonication caused reduced cohesion and caking properties of GMPs compared with the control. Also, lower compaction levels at different flow rates were determined in the sonicated samples. In general, powder flow analyses showed that sonication improved GMP flow behaviour. Sonicated samples had reduced microbial load compared with the control.
AtıfScopus12WoS8OpenAlex11İncele - MakaleYalnız künye2022Extinction properties of solutions for a parabolic equation with a parametric variable exponent nonlinearity
Ayazoglu Mashiyev, Rabil; Akkoyunlu, Ebubekir
In this paper, we study a class of p(·)-Laplace equation including nonstandard growth nonlinearity in a bounded smooth domain with homogeneous Dirichlet boundary condition. We establish the conditions of non-extinction and extinction are studied of global weak solutions in finite time for any initial data u0 . Moreover, we show the global existence results for N ≥ 1 with constant p for any initial data u0 .
AtıfScopus2İncele - MakaleAçık Erişim2022Scopus SJRQ4Mathematical language of students with learning disabilities in the context of length
Güven, Dilsad; Argün, Ziya
Mathematics is language dependent. Part of learning mathematics is learning the mathematical language. Learning disabilities are defined as disorders that are related to listening, thinking, speaking, writing, and reading that are seen in the processes of understanding or using a verbal or written language. In this context, the present study aimed to reveal the understanding and usage of the mathematical language of students with learning disabilities in the context of the concept of length. This study was conducted as a case study. The participants of the study were 4th grade and 5th grade students with learning disabilities. Data collection was conducted through semi-structured clinical interviews during a teaching experiment based on the concept of length and analysed using the content analysis method. According to the findings, the students with learning disabilities had a different and limited understanding, as well as usage of various mathematical terms including length, height, perimeter, half and centimetre.
AtıfScopus3OpenAlex3İncele - MakaleAçık Erişim2022Scopus SJRQ2Characterization of Essential Oil and Wastewater from Thymus nummularius M. Bieb. and Micromorphological Examination of Glandular Trichomes
Gerçek, Yusuf Can; Bayram, Sinan; Çelik, Saffet; Canlı, Deniz; Mavaldi, Muhammed Halid; Boztas, Kadir; Bastürk, Fatma Nur; Kırkıncı, Seran; Yesil, Yeter; Kösesakal, Taylan
This study aimed to determine the volatile profile by GC-MS and antimicrobial activity of the essential oil isolated from Thymus nummularius using the microwave-assisted hydrodistillation method and morphologically characterize the glandular trichomes in leaf samples. Obtained essential oil, as well as wastewater obtained during essential oil isolation, were chemically (polyphenolic compounds, organic acids, total phenolic content, total flavonoid content and antioxidant activity) characterized. As a result of GC-MS analysis of the essential oil, different ratios of essential oil components were identified, predominantly thymol (38.91%), linalool (13.12%) and geraniol (6.51%). The antimicrobial activity results showed that T. nummularius essential oil has a broad-spectrum inhibitory effect against all target microorganisms (bacteria and yeast-like fungi). Screening of 32 polyphenolic compounds and 52 organic acids in the wastewater was performed by LC-MS/MS and the major polyphenolic compound and organic acid were determined as caffeic acid (97316.85 µg/kg) and malic acid (6898.88 mg/kg), respectively. While the total phenolic and flavonoid content of the wastewater were 35.91 mg GA/g and 34.91 mg QE/g, respectively, the antioxidant activity results were obtained using the CUPRAC, CERAC and ABTS tests were 86.28 mg TE/g, 72.85 mg TE/g and 47.88 mg TE/g. These results support that the T. nummularius, an important production area in Turkey, can be used in different industrial areas due to its rich bioactive content. In addition, it can be said that wastewater is also considered a valuable source of bioactive substances.
AtıfScopus11WoS8OpenAlex11İncele - MakaleAçık Erişim2022Scopus SJRQ1Molecular Cloning, Expression and Characterisation of a Bacterial Myrosinase from Citrobacter Wye1
Cebeci, Fatma; Mayer, Melinda J.; Rossiter, John T.; Mithen, Richard; Narbad, Arjan
Glucosinolates are plant natural products which on degradation by myrosinases give rise to the beneficial bioactive isothiocyanates. Recently, a myrosinase activity was detected in a Citrobacter strain isolated from soil. This enzyme was purified enabling its amino acid sequence and gene sequence (cmyr) to be determined. In order to study this myrosinase it was necessary to establish an expression system that would enable future work such as a structural determination of the protein to be carried out. The myrosinase gene was amplified, cloned and expressed in Escherichia coli with a 6XHis-tag. The heterologous expression of cmyr enabled relatively large amounts of myrosinase to be produced (3.4 mg cmyr/100 ml culture). Myrosinase activity was determined by mixing substrate and enzyme and determining glucose release. Optimum pH and temperature were determined to be pH 6.0 and 25 °C for the Ni-NTA purified protein. The kinetic parameters of the purified myrosinase were determined using sinigrin as a substrate. Km and Vmax were estimated as 0.18 mM and 0.033 mmol/min/mg respectively for sinigrin under optimum conditions and compared to other kinetic data for myrosinases. The substrate specificity of myrosinase was determined having the highest affinity for sinigrin followed by glucoiberin, progoitrin, glucoerucin, glucoraphanin and glucotropaeolin.
AtıfScopus21WoS14OpenAlex16İncele