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Koleksiyondaki öğeler
- MakaleAçık Erişim2016Scopus SJRQ2Effect of external magnetic field on the Kβ/Kα X-ray intensity ratios of TixNi1-x alloys excited by 59.54 and 22.69 keV photons
Perişanoğlu, Ufuk; Alım, Bünyamin; Uğurlu, Mine; Demir, Lütfü
The effects of external magnetic field and exciting photon energies on the Kβ/Kα X-ray intensity ratios of various alloy compositions of Ti-Ni transition metal alloys have been investigated in this work using X-ray fluorescence spectroscopy. The spectrum of characteristic K-X-ray photons from pure Ti, pure Ni and TixNi1-x (x=0.30; 0.40; 0.50; 0.60; 0.70) alloys were detected with a high resolution Si (Li) solid-state detector. Firstly, Kβ/Kα X-ray intensity ratios of pure Ti, pure Ni and TixNi1-x alloys were measured following excitation by 59.54 keV γ-rays from a 200 mCi 241Am radioactive point source without any magnetic field and under 0.5 and 1 T external magnetic fields, separately. Later, the same measurements were repeated under the same experimental conditions for 22.69 keV X-rays from a 370 MBq109Cd radioactive point source. The results obtained for Kβ/Kα X-ray intensity ratios of pure Ti, pure Ni, Ti and Ni in various Ti-Ni alloys were evaluated in terms of both external magnetic field effect and exciting photon energy effect. When the results obtained for both exciting photon energies are evaluated in terms of changing of Kβ/Kα X-ray intensity ratios depending on the alloy composition, the tendency of these changes are observed to be similar. Also, Kβ/Kα X-ray intensity ratios for all samples examined have changed with increasing external magnetic field. Therefore, the results obtained have shown that Kβ/Kα X-ray intensity ratios of Ti and Ni in TixNi1−x alloys are connected with the external magnetic field. The present study makes it possible to perform reliable interpretation of experimental Kβ/Kα X-ray intensity ratios for Ti, Ni and TixNi1−x alloys and can also provide quantitative information about the changes of the Kβ/Kα X-ray intensity ratios of these metals with alloy composition.
AtıfScopus32WoS31OpenAlex32
İncele - MakaleAçık Erişim2018An investigation into the learning of ecological concepts
Toman, Ufuk
The aim of this research; secondary, high school and university levels of the students to understand the concepts related to ecology of Bayburt in Turkey. In this study, a progressive research method was used. In this method, conceptual understanding test was used as data collection tool. Open-ended test questions were used in this study. The test consisted of 150 students, 50 were from the secondary school, 50 were from the high school and 50 from the university in Bayburt. The data obtained from the test indic ate that the meanings of the ecological concept are in different categories and that this concept is not fully understood by the students at all three levels of learning. While students at secondary level relate the concepts related to ecology to their everyday use, high school and university students have more scientific definitions in their descriptions. In addition, misconceptions regarding these concepts have been identified at all levels of learning.
AtıfScopus4OpenAlex5İncele - MakaleAçık Erişim2017Scopus SJRQ1Enhancing the Damping Behavior of Dilute Zn-0.3Al Alloy by Equal Channel Angular Pressing
Demirtas, M.; Atli, K.C.; Yanar, H.; Purcek, G.
The effect of grain size on the damping capacity of a dilute Zn-0.3Al alloy was investigated. It was found that there was a critical strain value (≈1 × 10−4) below and above which damping of Zn-0.3Al showed dynamic and static/dynamic hysteresis behavior, respectively. In the dynamic hysteresis region, damping resulted from viscous sliding of phase/grain boundaries, and decreasing grain size increased the damping capacity. While the quenched sample with 100 to 250 µm grain size showed very limited damping capacity with a loss factor tanδ of less than 0.007, decreasing grain size down to 2 µm by equal channel angular pressing (ECAP) increased tanδ to 0.100 in this region. Dynamic recrystallization due to microplasticity at the sample surface was proposed as the damping mechanism for the first time in the region where the alloy showed the combined aspects of dynamic and static hysteresis damping. In this region, tanδ increased with increasing strain amplitude, and ECAPed sample showed a tanδ value of 0.256 at a strain amplitude of 2 × 10−3, the highest recorded so far in the damping capacity-related studies on ZA alloys.
AtıfScopus8WoS7OpenAlex7İncele - MakaleAçık Erişim2016Scopus SJRQ3Additional operation learning process to the mild intellectual disabilities students by means of virtual manipulatives: A multiple case study
Öztürk, Mesut; Akkan, Yaşar; Büyüksevindik, Baki; Kaplan, Abdullah
It is frequently emphasized that technology integration to the education of the students have intellectual disabilities has great importance. The researches performed show that using virtual manipulatives consist positive effects on learning mathematics on the students have intellectual disabilities. This study was done to investigate the addition operation learning process of the students have intellectual disabilities. Two students have mild intellectual disabilities and are 14 and 17 years old participated to this research conducted by means of multiple case study is one of the qualitative research designs. In this study was realized during five schedules data were collected through interviews, observations and documents. Content analysis were used for data analysis. At the end of the analysis, three categories of findings on "Learning of the addition operation", "Opinions on the use of computer and virtual manipulatives" and "Individual differences", were structured.
AtıfScopus2WoS3OpenAlex5İncele - MakaleYalnız künye2017Scopus SJRQ2Optical and Surface Characteristics of Mg-Doped GaAs Nanocrystalline Thin Film Deposited by Thermionic Vacuum Arc Technique
Pat, Suat; Özen, Soner; Şenay, Volkan; Korkmaz, Şadan
Magnesium (Mg) is the most promising p-type dopant for gallium arsenide (GaAs) semiconductor technology. Mg-doped GaAs nanocrystalline thin film has been deposited at room temperature by the thermionic vacuum arc technique, a rapid deposition method for production of doped GaAs material. The microstructure and surface and optical properties of the deposited sample were investigated by x-ray diffraction analysis, scanning electron microscopy, energy-dispersive x-ray spectroscopy, atomic force microscopy, ultraviolet–visible spectrophotometry, and interferometry. The crystalline direction of the deposited sample was determined to be (220) plane and (331) plane at 44.53° and 72.30°, respectively. The Mg-doped GaAs nanocrystalline sample showed high transmittance.
AtıfScopus19WoS5OpenAlex59İncele - MakaleYalnız künye2018Scopus SJRQ2Infinitely many solutions for a class of stationary Schrödinger equations with non-standard growth
Ayazoglu (Mashiyev), R.; Alisoy, Gulizar
In this paper, we study the existence of infinitely many solutions for a class of stationary Schrödinger type equations in ℝN involving the p(x)-Laplacian. The non-linearity is superlinear but does not satisfy the Ambrosetti-Rabinowitz type condition. The main arguments are based on the geometry supplied by Fountain Theorem. We also establish a Bartsch type compact embedding theorem for variable exponent spaces.
AtıfScopus2WoS1OpenAlex2İncele - MakaleAçık Erişim2019Scopus SJRQ3Examination of prospective teachers' perceptions of homeland: A phenomenological study
Degirmenci, Yavuz
Homeland can be described as the territory in which people who are bound to each other with several ties and have common values. It's one of the most valuable heritages which has been left to us from former generations, and will be transformed to future generations. There are great responsibilities on us, families, education and especially our teachers as an important elements of education to protect and transfer it to future generations. The reason is that patriotism begins in the family and continues in educational environments. An examination of the renewed primary and secondary education programs in terms of general objectives and contents revealed that there is a conscious effort for children to gain such values as consciousness and love for the homeland, and patriotism in especially social sciences and geography classes. Therefore, perceptions of prospective teachers regarding homeland, who will raise future generations, are important. The purpose of this research is to study perceptions of prospective teachers regarding the concept of homeland. The population of the study consists of 157 prospective classroom teachers, 98 of whom are females and 59 males, who were being educated in three different departments (social studies, Turkish and classroom teaching) in the Fall semester of 2018-2019 Academic Year. Phenomenology, a qualitative research method, has been employed in the research. The data collected were analyzed by the technique of content analysis. According to the findings of the research, the prospective social studies teachers came up with 28, prospective classroom teachers came up with 27 and prospective Turkish teachers came up with 28 valid metaphors about the concept of homeland, which makes a total of 83 different metaphors. In addition, the participants' most preferred metaphors about the concept were the metaphors of mother, home, family, house and earth.
AtıfScopus4OpenAlex2TR Dizin4
İncele - MakaleAçık Erişim2015Scopus SJRQ2Impact of exopolysaccharide production on functional properties of some Lactobacillus salivarius strains
Mercan, Emin; İspirli, Hümeyra; Sert, Durmuş; Yılmaz, Mustafa Tahsin; Dertli, Enes
The aim of this work was to characterize functional properties of Lactobacillus salivarius strains isolated from chicken feces. Detection of genes responsible for exopolysaccharide (EPS) production revealed that all strains harbored a dextransucrase gene, but p-gtf gene was only detected in strain E4. Analysis of EPS production levels showed significant alterations among strains tested. Biofilm formation was found to be medium composition dependant, and there was a negative correlation with biofilm formation and EPS production. Autoaggregation properties and coaggregation of L. salivarius strains with chicken pathogens were appeared to be specific at strain level. An increment in bacterial adhesion to chicken gut explants was observed in L. salivarius strains with the reduction in EPS production levels. This study showed that strain-specific properties can determine the functional properties of L. salivarius strains, and the interference of these properties might be crucial for final selection of these strains for technological purposes.
AtıfScopus19WoS16OpenAlex21İncele - BildiriYalnız künye2016Investigation of the surface free energy of the ITO thin films deposited under different working pressure
Özen, Soner; Şenay, Volkan; Pat, Suat; Korkmaz, Şadan
This study discusses the influence of working pressure on the surface energy of the ITO thin films produced by radio frequency magnetron sputtering method. Optical tensiometer (Attension Theta Lite) is used for evaluating wetting behavior of the water droplet on the film surface and Equation of State method was selected to determine surface free energy for this study. Equation of state method does not divide the surface tension into different components such as polar, dispersive, acid-base. It is calculated the surfaces' free energy measuring the contact angle with a single liquid. The surface free energy value was in the range of 15-31 mN/m. Also, the transmittances were determined in the wavelength range between 200 and 1000 nm using the UNICO 4802 UV-Vis double beam spectrophotometer. Transmittances of the produced ITO thin films are greater than %70 in the visible range.
AtıfScopus1WoS1OpenAlex1İncele - MakaleAçık Erişim2018Scopus SJRQ1Glucan type exopolysaccharide (EPS) shows prebiotic effect and reduces syneresis in chocolate pudding
İspirli, Hümeyra; Demirbaş, Fatmanur; Dertli, Enes
Exopolysaccharides (EPS) of lactic acid bacteria are important biopolymers that can improve the physicochemical properties of food products and act as prebiotics. In this study the physicochemical role and the prebiotic effects of a glucan type EPS with (α1-3) and (α1-6) linkages were assessed in chocolate pudding containing Lactobacillus rhamnosus GG as a probiotic strain. The functions of EPS were determined by developing three different formulations: control, probiotic (Lactobacillus GG) and symbiotic pudding (Lactobacillus GG + EPS) samples. The pH and acidity of the symbiotic pudding sample were higher than the probiotic and the control samples during the 28-day of storage period. Similarly, an important level of increment in Lactobacillus GG levels in symbiotic sample was observed compared to the probiotic sample suggesting the prebiotic role of the α-glucan. Importantly, the syneresis in symbiotic pudding sample reduced significantly compared to other pudding samples which is related with the physicochemical role of glucan type EPS. This study reveals the prebiotic and physicochemical roles of α-glucan type EPS in a chocolate pudding model.
AtıfScopus33WoS28OpenAlex35İncele - MakaleAçık Erişim2013Scopus SJRQ4Protective Role of Mentha longifolia L. ssp. longifolia against Aflatoxin B
Ceker, Selcuk; Agar, Guleray; Alpsoy, Lokman; Nardemir, Gokce; Kizil, Hamit Emre; Mete, Ebru
The aim of this study was to investigate the effects of essential oil of Mentha longifolia L. ssp. longifolia, used since ancient times for the treatment of many digestive tract diseases, on the genotoxicity and oxidative stress by a single dose of Aflatoxin B1 (5 μM) in the human lymphocyte culture. The total of the 12 identified components accounted for 97.69 % by Gas chromatography (GC). Major components of the oil were cis-piperitone epoxide (26.52 %), piperitenone oxide (26.40 %), pulegone (15.66 %) and piperitenone (13.57 %). According to the results obtained from GC-MS systems, monoterpenes consist of 89.19 % of the total oil approximately while sesquiterpenes were represented in small quantities in the oil. We studied the anti-genotoxic effects of essential oils of M. longifolia (MEO) by using sister chromatid exchange (SCE) and micronucleus (MN) test systems. Also, the anti-oxidative effects of MEO were evaluated by using superoxide dismutase (SOD), glutathione peroxidase (GPx) and malondialdehyde (MDA) assay. The SCE frequency and the number of MN were increased when treated with AFB1. Especially, MEO at 1.5 and 2.0 μl reduced SCE frequency and MN number in the human lymphocyte (p <0.05). In addition, AFB1 treatment significantly reduced the activity of SOD and GPx and elevated the level of MDA (p<0.05). MEOs treatment led to significant attenuation of AFB1-induced oxidative stress by normalization of the activities of SOD and GPx and the MDA (p < 0.05). These results suggest that MEOs could provide anti-oxidative and anti-genotoxic protection for the oxidative and genotoxic agents that cause many diseases including cancer and neurodegenerative disease.
AtıfScopus10WoS11OpenAlex11İncele - MakaleYalnız künye2016Scopus SJRQ2Morphological and optical comparison of the Si doped GaN thin film deposited onto the transparent substrates
Ozen, Soner; Senay, Volkan; Pat, Suat; Korkmaz, Sadan
The aim of this paper is to expand the body of knowledge about the silicon doped gallium nitride thin films deposited on different substrates. The physical properties of the Si doped GaN thin films deposited on the glass and polyethylene terephthalate substrates by thermionic vacuum arc which is plasma production technique were investigated. Thermionic vacuum arc method is a method of producing pure material plasma. The Si doped GaN thin films were analyzed using the following methods and the devices: atomic force microscopy, X-ray diffraction device, spectroscopic ellipsometer and energy dispersive X-ray spectroscopy detector. The produced Si doped GaN thin films are in the (113) orientation. The thicknesses and refractive index were determined by using Cauchy dispersion model. Surface morphologies of produced thin films are homogenous and low roughness. Our analysis showed that the thermionic vacuum arc method present important advantages for optical and industrial applications.
AtıfScopus8WoS7OpenAlex10İncele - Derleme MakaleAçık Erişim2018Scopus SJRQ1Concentrating photovoltaic thermal (CPVT) collectors and systems: Theory, performance assessment and applications
Daneshazarian, Reza; Cuce, Erdem; Cuce, Pinar Mert; Sher, Farooq
Concentrating photovoltaic thermal (CPVT) collectors and systems are very popular in both domestic and industrial solar energy applications. CPVT collectors provides incomparably greater thermal and electrical outputs compared to stand alone PV or hybrid PVT systems as incoming solar energy is maximised inside the unit via energy-efficient concentrators. Within the scope of this paper, a comprehensive review on CPVT collectors and systems is proposed. For an easier assessment of the findings through state-of-the-art analyses on CPVT collectors, the review is presented in a thematic way. Historical overview of the technology is followed by the detailed description of a CPVT collector with main system elements and thermodynamic performance definitions. The review also covers thermal and electrical performance analysis of CPVT collectors using water or air as working fluid, analytical, numerical, simulation and experimental works for performance evaluation of different design configurations of CPVT systems and qualitative analysis of electrical and thermal energy generation. The impacts of concentrator type and concentration ratio on system efficiency, operating temperature and coefficient of performance (COP) are analysed in detail. It is observed from the findings that CPVT collectors are promising devices in market, and they have a good potential to be competitive with conventional power generation systems in the near future.
AtıfScopus193WoS174OpenAlex214İncele - BildiriYayıncıda açık erişim2016Scopus SJRQ4Exergy analysis of a combined power and cooling cycle
Karaali, R.
Ammonia-water power cycles are important for efficient utilization of low temperature heat sources such as geothermal, solar, waste heat sources, etc. For some special conditions ammonia-water power cycle is an important and economical option. This paper presents an exergetic analysis of a combined power and cooling cycle that uses ammonia-water mixture as working fluid. Such cycles, use solar or geothermal energy or waste heat energy from a conventional power cycle. Ammonia-water power cycle can be used as independent cycles to provide power output and cooling. For a range (25-55 Bar) of boiler pressure the performance of the combined power and cooling cycle is investigated. The exergy of the boiler is very low compared to its energy. There is a boiling process and a heat transfer process at low temperature, both of which destruct the energy given to the boiler, so that the energy efficiency is low; however the exergy efficiency is higher than the energy efficiency. Increasing the turbine inlet pressure decreases the energy and exergy efficiencies.
AtıfScopus13WoS12OpenAlex75İncele - MakaleAçık Erişim2015Scopus SJRQ1Determination of Reference-Plane Invariant, Thickness-Independent, and Broadband Constitutive Parameters of Thin Materials
Hasar, Ugur C.; Kaya, Yunus; Barroso, Joaquim José; Ertugrul, Mehmet
We propose an effective microwave method for reference-plane-invariant and thickness-independent constitutive parameters measurement of thin materials. A function depending only on the interface reflection coefficient to facilitate fast computations of constitutive parameters is derived. In addition to the extraction of sample thickness, the method can also be applied to unique retrieval of constitutive parameters whose electromagnetic properties are yet unknown. We have performed an uncertainty analysis to examine how the accuracy of the method can be improved. Finally, we have compared the proposed method with other similar methods in the literature using measurements of distilled water and a thinner Plexiglas sample (1 mm). From the comparison, we note that the accuracy of our proposed method is not affected by any inaccurate knowledge of reference-plane positions and the sample length (or both) while those of compared methods are seriously decreased.
AtıfScopus53WoS52OpenAlex52İncele - MakaleAçık Erişim2015Scopus SJRQ3The effect of self-construal on statue and role-relaxed consumption
Başar, Enes Emre; Erciş, Aysel
Consumer behavior researches indicate that individuals prefer the products which are compatible with themselves. For instance, individuals with highly independent-self take into account the functional benefits whereas individuals with highly interdependent-self take into account the symbolic benefits on their product preferences. Related studies in literature show that there are two different consumption patterns, which are called statue and role-relaxed consumptions, those take the lead on explaining consumers’ brand or product preferences. Statue consumption concentrates on symbolic meanings of the products, whereas role-relaxed consumption focuses on the functional benefits. This research examines the effects of self-construal on statue and role-relaxed consumption patterns with reference to the close relationships of independent self and interdependent self with role-relaxed consumption and statue consumption, respectively. The results indicate that self-construal has significant effects on statue and role-relaxed consumption.
AtıfOpenAlex2İncele - MakaleAçık Erişim2015Scopus SJRQ1Investigation on the morphology and surface free energy of the AlGaN thin film
Özen, Soner; Şenay, Volkan; Pat, Suat; Korkmaz, Şadan
The purpose of this paper is to analyze surface properties of AlGaN thin film produced using thermionic vacuum arc technique. Thermionic vacuum arc is an alternative deposition technique for GaN thin films that produces in a very short production time for GaN-based solid-state applications. XRD results showed that AlGaN thin film with cubic crystal structure on a amorphous glass was grown. Conductivity type of AlGaN thin film is determined as p-type by hot-probe method which is a very simple method. The surface morphology was analyzed and discussed using field emission scanning electron microscopy (FESEM) and atomic force microscopy. The contact angles in four different testing liquid and surface free energy of the AlGaN thin film were investigated by optical tensiometer.
AtıfScopus27WoS27OpenAlex28İncele - MakaleAçık Erişim2017Scopus SJRQ2The status of renewable electricity from hydropower in Turkey
Serencam, Uğur
Turkey has many problems due to its increasing energy consumption and rapid economic growth. Foreign energy dependency adversely affects sustainable development of the country by hindering its economic development. Turkey has a yearly total 433 TWh hydropower capacity and 151 TWh yearly economical capacity. The electricity demand of Turkey will reach to around 420 TWh annually by 2020. Turkey had 521 operational hydropower plants with a total capacity of almost 24,000 MW in 2014. This corresponds to 34% of the total capacity. Within the first 8 months of 2015, 8 more hydropower plants came online with a capacity of around 1,240 MW. The share of hydro in power generation capacity went up by 1% during the first five months of the year reaching 35% from its previous 34% level in 2014.
AtıfScopus2WoS2OpenAlex2İncele - Derleme MakaleAçık Erişim2017Scopus SJRQ1Correlation coefficient of single-valued neutrosophic hesitant fuzzy sets and its applications in decision making
Şahin, Rıdvan; Liu, Peide
As a combination of the hesitant fuzzy set (HFS) and the single-valued neutrosophic set (SVNS), the single-valued neutrosophic hesitant fuzzy set (SVNHFS) is an important concept to handle uncertain and vague information existing in real life, which consists of three membership functions including hesitancy, as the truth-hesitancy membership function, the indeterminacy-hesitancy membership function and the falsity-hesitancy membership function, and encompasses the fuzzy set, intuitionistic fuzzy set (IFS), HFS, dual hesitant fuzzy set (DHFS) and SVNS. Correlation and correlation coefficient have been applied widely in many research domains and practical fields. This paper, motivated by the idea of correlation coefficients derived for HFSs, IFSs, DHFSs and SVNSs, focuses on the correlation and correlation coefficient of SVNHFSs and investigates their some basic properties in detail. By using the weighted correlation coefficient information between each alternative and the optimal alternative, a decision-making method is established to handling the single-valued neutrosophic hesitant fuzzy information. Finally, an effective example is used to demonstrate the validity and applicability of the proposed approach in decision making, and the relationship between the each existing method and the developed method is given as a comparison study.
AtıfScopus118WoS94OpenAlex108İncele - MakaleAçık Erişim2017Scopus SJRQ1Thermal regulation impact of green walls: An experimental and numerical investigation
Cuce, Erdem
Green walls can be basically defined as climbing plants grown either directly against, or on support structures integrated to external building walls. Similar to other types of green infrastructure, they are in the centre of interest owing to their remarkable benefits such as reducing internal building temperatures, mitigating building energy consumption and facilitating urban adaptation to a warming climate. In this research, thermal regulation feature of green wall systems is experimentally and numerically investigated through a case study conducted in the Jubilee Campus of University of Nottingham. Internal wall temperatures are measured time-dependently for different cases and the results are compared with those of ordinary walls for a reliable and realistic approach. Different sky conditions are also considered within the scope of this research as an independent variable. Experimental results are verified by numerical models carried out in Ecotect. The results reveal that an average of 2.5 °C reduction in internal wall temperature can be achieved via green walls with about 10 cm thick climbing vegetation of Hedera helix, which is very promising.
AtıfScopus168WoS138OpenAlex178İncele
