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Acta Oecologica1
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Acta Physiologiae Plantarum1
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Biochemical Systematics and Ecology,1
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Colloids and Surfaces A: Physicochemical and Engineering Aspects1
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European Journal of Psychology of Education1
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International Journal of Science and Mathematics Education1
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Materials Chemistry and Physics1
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Materials Science and Engineering: B1
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Surface and Interface Analysis1
Responses of antioxidant defense system of Helianthus annuus to abscisic acid treatment under drought and waterlogging.
Yüksel Keleş, Serpil Ünyayar
The effect of abscisic acid (ABA) treatment on growth pigments and antioxidant defense system were in vestigated in seedlings of Helianthus annuus (cvs. Nantio F1 and Özde mirbey) subjected to drought and waterlogging stress. In addition, seedlings were sprayed with 10 µM ABA three times every other day. Reltive growth rate (RGR) was significantly reduced in both genotypes under drought stress, however, this growth inhibition was less in ABA-treated plants. Total chlorophyll content increased by drought stress in both gentypes. Ascorbate was not influenced by drought, while α-tocopherol in creased in cv. Nantio F1. Ascorbate and α-tocopherol in creased with drought stress in cv. Özdemirbey. ABA treat ment de creased ascorbate and ß-carotene contents while it increased α-tocopherol and xan...
A highly efficient catalyst consisting of Ni and S double-doped reduced graphene modified with ZnO nanoparticles for hydrogen peroxide electroreduction
Sedef Kaplan A, Rukan Suna Karatekin A
n this study, we prepared a novel electrocatalyst based on S doped reduced graphene layer modified with Ni and ZnO nanoparticles. The catalyst materials were characterized by X-ray Powder Diffraction (XRD), Raman spectroscopy, UV–vis spectroscopy, Scanning Electron Microscopy (SEM), Energy Dispersive X-ray Spectroscopy (EDX), and mapping. Because of the synergistic effect between three materials (S, Ni, and ZnO), the new electrocatalyst finally formed with a large electroactive surface area. Through the measurement, it was concluded that this surface includes large active sites which can effectively improve the electron transfer rate. The electrocatalytic activity of Ni-ZnO@s-rGO toward H2O2 reduction was examined via some measurements such as CV, I-t measurement, and electrochemical imped...
Corrosion inhibition of indole-3-acetic acid on mild steel in 0.5 M HCl
Avcı, Gülşen
Corrosion inhibition of indole-3-acetic acid on mild steel in acidic medium (0.5 M HCl) containing the desired amount of inhibitor has been investigated at different temperatures by using potentiodynamic polarization, electrochemical impedance spectroscopy, and polarization resistance measurements. The experimental results showed that corrosion potential shifted toward a more negative potential region in the presence of indole-3-acetic acid than that of blank solution. According to the obtained results from all measurements, inhibition efficiency was about 77% with 1.7 × 10−3 M inhibitor present, increasing to about 93% at the 1 × 10−2 M inhibitor concentration. Potentiodynamic polarization measurements showed that the current at anodic and cathodic regions obtains a smaller value in the p...
Aqueous extract of Acacia cyanophylla leaves as environmentally friendly inhibitor for mild steel corrosion in 1 MH2SO4 solution
Gülşen Avcı, Yüksel Keleş
The efficiency of Acacia cyanophylla leaves extract as an environmentally friendly inhibitor for mild steel in aerated aqueous 1M H2SO4 solution has been investigated by potentiodynamic polarization measurements and electrochemical impedance spectroscopy techniques. Addition of inhibitor decreases the corrosion current whereas the corrosion potential values show slight shifts in positive directions. Inhibition efficiency was found to be about 93% (the maximum value was determined from the polarization curve). Efficiencies obtained from both electrochemical techniques are in good agreement. Adsorption of acacia cyanophylla leaves extracton mild steel surface in 1 M H2SO4 solution obeys Langmuir adsorption isotherm. Polarization curves were also obtained at different temperatures in order to...
The role of biochemical regulation on the adaptation of gypsophile and gypsovag species
Fazilet Özlem Çekiç, Yüksel Keleş
There are two groups of plant species that spread in gypsiferous soils. While gypsophytes only grow on gypsi ferous soils, gypsovags can grow on both gypsum and non-gypsum soil. Adaptation of plants to gypsum soils requires biochemical arrangements in addition to proper morphological and physiological characteristics. In this study, three gypsophyte species and on-gypsum and non-gypsum speciments of three gypsovag species were examined for antioxidant capacities. The average phenolic substance contents were 126.5, 30.5 and 37.6 μgg−1 DW in gypsophile, on-gypsum and in non-gypsum gypsovag species respectively. Gypsophyte, Thymus leucos tomus var. gypsaceus species was identified as having seven different phenolic compounds and the highest phenolic substance content. However, phenolic subst...
Identifying competency demands in calculus textbook examples: The case of integrals
Özgeldi, Meriç
This study investigates how three widely used calculus textbooks realise integrals as a potential to prompt mathematical competencies, adapting the rating scheme used in Boesen et al. (The Journal of Mathematical Behavior, 33:72–87, 2014), Pettersen and Braeken (International Journal of Science and Mathematics Education, 17(2):405–425, 2019) and Turner, Blum and Niss (2015). For this purpose, the study analysed examples (n = 444) about integrals—specifically, to assess the extent to which solving those examples calls for the activation of a particular set of mathematical competencies:Communication; Devising Strategies; Mathematising; Representation; Using Symbols,Operations and Formal Language [Symbols and Formalism]; Reasoning and Argument. The competency demand of the examples was ...
What’s metacognition got to do with the relationship between test anxiety and mathematics achievement?
Özgeldi, Meriç
Research examining the joint relationships between test anxiety, metacognition, and mathematics achievement revealing the mediational role of metacognition in the relationship between test anxiety and mathematics achievement is sparse. A mediation study was designed to redress this imbalance. The Children’s Test Anxiety Scale (CTAS), Junior Metacognitive Awareness Inventory (Jr. MAI), and Mathematics Achievement Test (MAT) were distributed to 943 (442 males and 501 females) Grade 7 (n = 477) and Grade 8 (n = 466) students aged between 11–12 (Mage = 11.5, SD = .88) and 11–13 (Mage = 12, SD = .91) years, respectively. In this study, multiple mediation models were tested to explore the role of metacognition as a mediator of the effect of test anxiety on mathematics achievement. Results indica...
Gülşen Avcı sciencedirect.com alanından [HTML] Inhibitor effect of N, N′-methylenediacrylamide on corrosion behavior of mild steel in 0.5 M HCl
Avcı, Gülşen
N,N′-Methylenediacrylamide has been evaluated as a corrosion inhibitor for mild steel electrodes in 0.5 M HCl solution using potentiodynamic polarization, electrochemical impedance spectroscopy, and polarization resistance measurements. According to the experimental results, inhibition efficiency increased with increasing inhibitor concentration. Potentiodynamic measurements showed that the presence of inhibitor molecules decreases cathodic and anodic currents and shifts corrosion potential to a more positive potential region. Adsorption of the inhibitor molecules to the mild steel surface obeyed the Langmuir adsorption isotherm. Adsorption free energy was calculated from the adsorption isotherm as −26.8 kJ mol−1. The negative value of ΔGads showed that the adsorption process is spontaneou...
Yemler Bilgisi Yem Teknolojisi ve Balık Besleme
Bilgüven, Murat
Her havuz alanında ya da yetiştirme biriminden elde edilen balık ve dolayısıyla balık yetiştiriciliğinin kârlılığı, büyük ölçüde kullanılan yemin miktarına bağlıdır. Su ürünleri sistemi ne kadar yoğun olursa yemlemenin önemi o kadar fazla olur ve toplam üretim maliyetinde yem maliyetinin payı da o kadar artar. Bilindiği üzere alabalık başta olmak üzere bazı balıkların yetiştiriciliği için akarsu sistemli tesisler kullanılmakta yada sıcaklığın, su bileşiminin ve akıntının dolayısıyla oksijen yoğunluğunun daha iyi olduğu tatlı su ve kıyılarda ise yüzer ağ kafeslerde yetiştiricilik yapılmaktadır. Su ürünleri yetiştiriciliğinin ileri durumda olduğu ülkelerde entansif yetiştiricilik uygulanmakta ve yetiştirme alanlarında birim hacimde maksimum ürün yetiştirilmeye çalışılmaktadır. Bu tür yetişti...
Role of antioxidant defense system and biochemical adaptation on stress tolerance of high mountain and steppe plants
Keleş, Yüksel
Eleven species were collected from Northwest Anatolian mountains (1500–2000 m) and 18 species were collected from the Central Anatolian steppes (850–1000 m) in June 1998 and 1999. In all the species investigated, the water and dry matter percentages and solute contents were measured. The chlorophyll, b-carotene, ascorbate and a-tocopherol contents and catalase (CAT), superoxide dismutase (SOD) andglutathione reductase (GR)enzymeactivities oftheplants werealsodetermined.Thesteppeplantshadlowerwatercontentcomparedwith alpine plants. The chlorophyll contents of the plants investigated did not change with altitude. However, the carotenoid/chlorophyll ratio of alpine plants was found to be significantly higher. The antioxidant/chlorophyll ratio of the trees and shrubs was higher than that of he...