Yayınlar
Koleksiyondaki öğeler
- MakaleYalnız künye2019Scopus SJRQ1Purification and biochemical characterization of a novel copper, zinc superoxide dismutase from liver of camel (Camelus dromedarius): An antioxidant enzyme with unique properties
Chafik, Abdelbasset; Essamadi, Abdelkhalid; Çelik, Safinur Yildirim; Mavi, Ahmet
A novel copper, zinc superoxide dismutase (CuZnSOD) was purified to homogeneity from the liver of an animal well adapted to the stressful living conditions of the desert, the camel (Camelus dromedarius). The biochemical properties of camel liver CuZnSOD were examined. The purified enzyme had a native molecular weight of 28 kDa, as judged by gel filtration chromatography, and showed a single band at 27 kDa on SDS-PAGE, indicating that it is a monomeric protein. Optimal activity of the purified enzyme occurred at 43 °C and pH 6.0, and the activation energy was 1.42 kJ/mol. CuZnSOD activity was strongly inhibited by β-ME, DTT, H 2 O 2 and SDS and slightly inhibited by EDTA, NaN 3 and PMSF. Al 3+ , Ca 2+ , Cd 2+ , Mg 2+ and Zn 2+ stimulated CuZnSOD activity, whereas Ba 2+ , Co 2+ , Fe 2+ and Ni 2+ inhibited it. The purified enzyme contained 0.010 µg of Cu and 0.69 µg of Zn per mg of protein. K m , V max , k cat and k cat /K m values for NBT and riboflavin were 16.27 and 0.16 µM, 20.85 and 21.54 U/mg, 9.65 and 9.97 s −1 , and 0.59 and 62.33 s -1 µM −1 , respectively. Camel liver CuZnSOD exhibited unique biochemical properties compared to those of other CuZnSODs, including lower molecular weight with a monomeric structure, higher optimum temperature, very low E a , very low optimum pH, very low contents of Cu and Zn, and higher affinity, turnover number and catalytic efficiency for riboflavin. These unique properties of camel liver CuZnSOD might be related to the ability of this animal to inhabit stressful desert conditions.
AtıfScopus26WoS23OpenAlex26
İncele - MakaleYalnız künye2016Scopus SJRQ3Organic acids, sugars and mineral content of cherry laurel (laurocerasus officinalis roem) accessions in Turkey
Esringu, Aslihan; Akšić, Milica Fotirić; Ercisli, Sezai; Okatan, Volkan; Gozlekci, Adiye; Cakir, Ozlem
In this study we report on the content of organic acids, sugars and miner-als in the pulps of the twelve cherry laurel accessions most commonly consumedin eastern Black Sea Region. Malic acid was the dominant organic acid rangedfrom 43.27 (CL6) to 54.23 (CL3) mg/100 g fresh weight basis. The dominantsugars were glucose and fructose in the pulps that ranged from 4.83 (CL1) to5.74 (CL5) mg/100 g and 4.66 (CL3) to 5.53 (CL7) mg/100 g, respectively. Thepulp of cherry laurel was shown to be rich in potassium (187-241 mg), phos-phorus (26-45 mg), calcium (15-22 mg), magnesium (15-24 mg) and sodium(3.9-6.1 mg) in 100 g fruit pulp. The data may be useful in selecting wild ediblefruit species appropriate for incorporation into diets.
AtıfScopus5İncele - Kitap BölümüYalnız künye2018Scopus SJRQ3Solar calculations of modified arch (Semi-spherical)-type greenhouse system for Bayburt City
Uğur, Çakir; Erol, Şahin; Kemal, Çomakli; Ayşegül, Çokgez Kuş
Solar energy is thought as the main source of all energy sources in the world, and it can be used in many applications like agricultural areas, heating-cooling or electricity production directly or indirectly. Greenhousing is the first one of the agricultural activities that solar energy can be used directly in. Greenhouses offer us suitable conditions which can be controlled easily for the growth of the plant, and they are made by using a covering material that allows the sunlight to enter into the system. Covering material can be glass, fibre glass, plastic or another transparent element. This study investigates the solar energy usability rates and solar energy benefitting rates of a semi-spherical (modified arch)-type greenhouse system according to different orientations and positions which exist under climatic conditions of Bayburt. In the concept of this study, it is tried to determine the best direction and best sizes of a semi-spherical greenhouse to get the best solar benefit from the sun. To achieve this aim, a modelling study is made by using MATLAB. However, this modelling study is run for some determined shapes and greenhouses, and it can be used for different shaped greenhouses or buildings. The basic parameters are determined as greenhouse azimuth angle, the rate of size of long edge to short and seasonal solar energy gaining of greenhouse.
AtıfScopus1OpenAlex2İncele - MakaleYalnız künye2018Scopus SJRQ1High temperature superplasticity and deformation behavior of naturally aged Zn-Al alloys with different phase compositions
Demirtas, M.; Kawasaki, M.; Yanar, H.; Purcek, G.
Two Zn-Al alloys, eutectoid Zn-22Al and dilute Zn-0.3Al, were processed through equal-channel angular pressing (ECAP). The ECAP-processed alloys were subjected to long-term natural aging at room temperature for 120 days in order to investigate the effect of long-term natural aging on high-temperature superplasticity and the deformation behavior of these alloys. The grain size of the Zn-22Al alloy increased from 200 nm after ECAP to 400 nm after the natural aging process. The Zn-0.3Al alloy with a grain size of 1.3 µm after ECAP demonstrated a reasonably stable microstructure with the grain size of ~ 1.7 µm after long-term natural aging. The naturally aged ultrafine-grained (UFG) Zn-22Al alloy showed an excellent superplastic elongation of about 1800% at 200 °C. Grain boundary sliding was determined as the dominant deformation mechanism in this alloy. On the contrary, a considerably low elongation to failure of 230% was recorded in the naturally aged fine-grained (FG) Zn-0.3Al alloy at 150 °C, and dislocation creep was evaluated as the main deformation mechanism for this alloy. Detailed microstructural analyses showed that the FG Zn-0.3Al alloy was exposed to grain boundary corrosion during the natural aging process due to the presence of Al precipitates at grain boundaries whereas such formation was not observed in the UFG Zn-22% Al alloy. Grain boundary sliding was hindered by grain boundary corrosion and the cavity nucleation at the corroded grain boundaries caused a premature failure leading to such a low elongation in the Zn-0.3Al alloy.
AtıfScopus30WoS30OpenAlex33İncele - MakaleYalnız künye2018Scopus SJRQ2Investigating 5-hydroxymethylfurfural formation kinetic and antioxidant activity in heat treated honey from different floral sources
Turkut, G. Merve; Degirmenci, Atiye; Yildiz, Oktay; Can, Zehra; Cavrar, Sevda; Yaylaci Karahalil, Fatma; Kolayli, Sevgi
The quality and biochemical properties of honey are affected by heating or during storage period. The most important biochemical reaction that occurs in this process is the Maillard reaction. HMF (5-hydroxymethylfurfural) is one of the major intermediate products in the Maillard reaction that can lead to quality reduction in heated honey. In this study, the effect of heating on the antioxidant activity, and colour values as Maillard reaction indicators of three different botanical honeys were investigated; the HMF formation was also determined. Temperatures of 50, 70 and 80 °C were applied on the honeys between 0 and 48 h. Total phenolic content, ferric reducing/antioxidant power and scavenging of 2,2-diphenyl-1-picrylhydrazyl free radical assays are used to determine the antioxidant capacity. Results showed that the formation of HMF and the antioxidant properties of honeys were significantly increased during the heating process. Pure HMF compound also showed lower antioxidant activity. The formation of HMF has higher degree of linearity in the fit of the zero order reaction and also it was the highest in the chestnut honey. Furthermore, it was found that as the biochemical value of the honeys increased, the HMF formation decelerated.
AtıfScopus45WoS35OpenAlex44İncele - MakaleAçık Erişim2019Scopus SJRQ3A study of wild plant species of brassicaceae family in bayburt region of Turkey
Gidik, Betül; Gül, Volkan; Sefali, Abdurrahman
The Brassicaceae (Cruciferae) is one of the most important groups and it has 338 genera and 3709 species around the worldwide. Plant samples of the Brassicaceae family were collected and photographed during the vegetation period of 2017. The plant samples and the photos were taken from their natural habitat between 23 April and 11 August 2017. The locations were determined based on differences in geographical features with variable ecological conditions. 38 genera and 80 species and subspecies were identified from different locations of the study area. Heldreichia bupleurifolia Boiss. subsp. rotundifolia, Aethionema caespitosum, Thlaspi lilacinum, Tchihatchewia isatidea, Bornmuellera cappadocica, Aurinia rupestris subsp. cyclocarpa, Alyssum stylare, Alyssum pseudomouradicum, Alyssum peltarioides Boiss. subsp. peltarioides are endemic taxa for Bayburt.
AtıfScopus6WoS3OpenAlex6İncele - MakaleAçık Erişim2017Scopus SJRQ3Lateral Position Effect of Auxiliary Permanent Magnets on the Magnetic Force Properties of Cylindrical YBCO
Abdioglu, M.; Kabaer, M.; Ozturk, K.; Erdem, O.; Celik, S.
The magnetic levitation force (MLF) and the guidance force (GF) should be improved for loading capacity and stability of Maglev systems, respectively. Although there are some ways to increase these properties, using of auxiliary onboard permanent magnets (PMs) can be considered as the most efficient one. The auxiliary PMs increase the MLF significantly but, at the same time, decrease the GF. We have searched a solution to overcome this problem in this study. Firstly, we have determined the optimum vertical positions of the auxiliary PMs and then we have investigated the vertical levitation force and lateral guidance force of hybrid Maglev system depending on lateral position of auxiliary PMs in different cooling heights (CHs). A cylindrical YBCO superconductor, fabricated by a top seeding method with the diameter of 45 mm and the height of 15 mm, was used as a high-temperature superconductor (HTS). The maximum increment rate in MLF and the minimum decrement rate in GF were observed as 277 and 54 %, respectively. The increment in MLF was obtained five times more than the decrement in GF, and this reality points out that the results of this study can be useful for improving the loading capacity and thus enhancing the practical applicability of Maglev systems.
AtıfScopus16WoS14OpenAlex14İncele - MakaleAçık Erişim2019Scopus SJRQ2Antimony removal from aqueous solutions using magnetic nickel ferrite (NiFe 2 O 4 ) nanoparticles
Karcioğlu Karakaş, Zeynep; Boncukcuoğlu, Recep; Karakaş, İbrahim Hakkı
In this study, magnetic nickel ferrite (NiFe 2 O 4 ) nanoparticles were synthesized via microwave assisted combustion method and these particles were used as adsorbent for antimony removal. The most effective parameters for the removal efficiency are adsorbent dosage and temperature, while the impact of pH is insignificant. In order to determine the most suitable kinetic model, the compatibility of pseudo-first order, pseudo-second order and the intraparticle diffusion model was compared and the most suitable kinetic model was determined to be pseudo-second-order. Langmuir and Freundlich isotherms were assessed and the most suitable isotherm was observed to be Freundlich model.
AtıfScopus6WoS3OpenAlex6İncele - MakaleAçık Erişim2015Scopus SJRQ2Analysis of technological pedagogical content knowledge studies in Turkey: A meta-synthesis study
Yilmaz, Gül Kaleli
The purpose of this research is to analyze the Technological Pedagogical Content Knowledge (TPACK) studies in Turkey by using meta-synthesis method and to present the type of tendency in this field. In the research, a total of 59 studies made up of 37 papers, 15 dissertations, and 7 assertions which were published between the years of 2008-2014 and chosen through purposeful sampling method were analyzed. Google Academics search engine, TÜB̄TAK ULAKB̄M DergiPark, YÖK National Dissertation Center, EBSCOhost-ERIC ve SPRINGER databases took advantages of selecting the studies. Each study were examined within the context of the study's purpose, subject area, method, sample, data collection tools, teaching applications and results by being subjected to content analysis. Obtained data were interpreted depending on the frequency and partly illustrated through tables and graphs. In the research, the results showed that a significant portion of the studies were conducted with the aims of scale validation/adaptation, examination of TPACK competences and developments; that a few number of studies focused on a special subject area; that survey study and data collection tolls such as scale/survey were used mostly; that studies conducted with prospective teachers were majority; that although it had been revealed that the participants usually have high levels of TPACK competence/perception in quantitative studies, the situation was contrary in qualitative weighted studies; that different teaching applications such as TPACK workshops, mixed vocational development program, blended learning increases TPACK. In light of the obtained results, it was seen that studies targeting TPACK development in which implementations are carried in a long process through using a quite number of data collection tools are needed in Turkey. Besides, it was recognized that the courses in education faculties should be re-updated according to TPACK and teachers or prospective teachers should be trained with the help of courses or in/pre-service training programs. Lastly, recommendations were made for researchers, program makers and appliers who will do studies in this field.
AtıfScopus16OpenAlex44İncele - MakaleAçık Erişim2015Scopus SJRQ4Synthesis, characterization and complexation properties of a novel Mg-porphyrazine with metal ions in acetonitrile-chloroform
Kabay, Nilgün; Baygu, Yasemin; Gök, Yaşar; Başoʇlu, Aysel; Ocak, Ümmühan
The synthesis and characterization of a novel metal derivative of a peripherally symmetrically tetra-substituted porphyrazine derived from 25,26-dioxa-6,7,9,10,15,16,18,19-octahydro-25H-1,24-methanodibenzo[q,t][1,4,13,16,17,10]tetraoxadithiacyclohenicosine-12,13-dicarbonitrile was carried out. The influence of metal cations such as Zn2+, Fe2+, Mn2+, Ni2+, Co2+, Hg2+ and Cu2+ on the spectroscopic properties of the ligands, the starting material dinitrile and MgPz were investigated in acetonitrile-chloroform solution (1/1) by means of absorption spectrometry. Absorption spectra showed isosbestic points in the spectrophotometric titration of Cu2+ and Hg2+ with MgPz ligand. The results of spectrophotometric titration experiments disclosed the complex stability constant of the novel ligand, MgPz with Cu2+ and Hg2+ cations.
- MakaleYalnız künye2017Scopus SJRQ1Purification of camel liver catalase by zinc chelate affinity chromatography and pH gradient elution: An enzyme with interesting properties
Chafik, Abdelbasset; Essamadi, Abdelkhalid; Çelik, Safinur Yildirim; Mavi, Ahmet
Climate change and increasing temperatures are global concerns. Camel (Camelus dromedarius) lives most of its life under high environmental stress in the desert and represent ideal model for studying desert adaptation among mammals. Catalase plays a key role in protecting cells against oxidative stress. For the first time, catalase from camel liver was purified to homogeneity by zinc chelate affinity chromatography using pH gradient elution, a better separation was obtained. A purification fold of 201.81 with 1.17% yield and a high specific activity of 1132539.37 U/mg were obtained. The native enzyme had a molecular weight of 268 kDa and was composed of four subunits of equal size (65 kDa). The enzyme showed optimal activity at a temperature of 45 °C and pH 7.2. Thiol reagents, β-Mercaptoethanol and D,L-Dithiothreitol, inhibited the enzyme activity. The enzyme was inhibited by Al3+, Cd2+ and Mg2+, whereas Ca2+, Co2+ and Ni2+ stimulated the catalase activity. Reduced glutathione has no effect on catalase activity. The Km and Vmax of the enzyme for hydrogen peroxide were 37.31 mM and 6185157 U/mg, respectively. Sodium azide inhibited the enzyme noncompetitively with Ki value of 14.43 μM, the IC50 was found to be 16.71 μM. The properties of camel catalase were different comparing to those of mammalian species. Relatively higher molecular weight, higher optimum temperature, protection of reduced glutathione from hydrogen peroxide oxidation and higher affinity for hydrogen peroxide and sodium azide, these could be explained by the fact that camel is able to live in the intense environmental stress in the desert.
AtıfScopus9WoS9OpenAlex10İncele - MakaleAçık Erişim2017Scopus SJRQ3The antioxidant activity, vitamin c contents, physical, chemical and sensory properties of ice cream supplemented with cornelian cherry (Cornus mas L.) paste; [Kızılcık (Cornus mas L.) ezmesi ılaveli dondurmanın antioksidan aktivitesi, C Vitamini ıçeriği, fiziksel, kimyasal ve duyusal özellikleri]
Topdaş, Elif Feyza; Çakmakçi, Songül; Çakiroğlu, Kübra
The aim of this research was to investigate the effect of cornelian cherry (Cornus mas L.) paste (CP) on the quality properties of ice cream. CP was added to an ice cream mix at four concentrations (0, 5, 10 and 15%, w/w) for ice cream production. The increment of CP level caused the increased of vitamin C content, a values and overrun values, whereas it decreased the viscosity of samples compared to Control ice cream sample. The results indicated that lyophilised water extracts of CP (LWECP) contain remarkable phenolic compounds. The findings showed that there is a positive correlation between the total phenolics and flavonoid contents in LWECP and ice cream samples antioxidant activity. CP has shown to be an effective source of natural antioxidants. CP may be used as a source of natural colour and flavour agent in ice cream manufacture. CP enhanced vitamin C amounts of ice cream, and improve sensory properties. In the literature surveys of Science Direct, Web of Science, Google Scholar and Scopus databases an ice cream study using cornelian cherry fruit was not found.
AtıfScopus29WoS25OpenAlex18İncele - MakaleAçık Erişim2017Scopus SJRQ1Improvement in levitation force performance of bulk MgB2 superconductors through coronene powder adding
Erdem, O.; Abdioglu, M.; Guner, S.B.; Celik, S.; Kucukomeroglu, T.
The effect of coronene (C24H12) addition on the levitation force properties of MgB2 superconductor has been investigated for the first time in this study. The polycrystalline disk-shaped MgB2 + y wt % C24H12 samples (y = 0, 2, 4, 6, 8, 10), were synthesized by a pellet/closed tube method at 850 °C under Ar atmosphere, after hot pressing at 200 °C. XRD analysis indicates a decrease in lattice parameters of coronene added samples and confirms substitution of carbon in boron sites. An increase in lattice strain and a decrease in grain size are observed due to the carbon substitution effect. Vertical and lateral levitation force measurements under zero-field-cooled and field-cooled regimes were carried out at different temperatures of 20, 25 and 30 K. It was found that the coronene addition significantly increases the high-field critical current density of MgB2. The Jc values were obtained as 4.6 × 103 Acm−2 and 1.3 × 104 Acm−2 for pure and 4 wt % coronene added samples at 20 K and 4 T. In addition, the levitation force measurements show that 4 wt % coronene adding is very effective in increasing both the vertical and lateral levitation force performances at 20 K. The maximum levitation force for 4 wt % coronene added sample corresponds to 7.58 N/g whereas the reference sample shows 6.73 N/g at 20 K in ZFC regime. The results point out that the hydrocarbon of C24H12 is an effective carbon-containing additive for MgB2 and can be useful for optimizing the levitation performance of MgB2 superconductors for potential applications.
AtıfScopus25WoS21OpenAlex27İncele - MakaleYalnız künye2018Scopus SJRQ1Conjugated polythiophene/Ni doped ZnO hetero bilayer nanocomposite thin films: Its structural, optical and photoluminescence properties
Bayram, Ozkan
In this study, synthesis and characterization of plasma polymerized Thiophene/ Nickel doped Zinc Oxide (PTNZO) bilayer nanocomposite films were carried out. Nickel doped zinc oxide (NZO) thin films were obtained by magnetron sputtering technique on glass substrates at 40 W Radio Frequency (RF) power. Plasma polymerized Thiophene (PT) thin films were deposited on the NZO thin films obtained on the glass substrate by Radio Frequency (RF) plasma polymerisation technique. X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM), FTIR and Photoluminescence (PL) analyzes were performed for the characterization of PTNZO hetero bilayer nanocomposite films. In the XRD spectra of PTNZO bilayer nanocomposite thin films, (002) planes were determined as the most basic peak, and it was determined that the intensity of this peak, changed depending on the RF power of polymer thin films. Optical properties of nanocomposite thin films such as transmittance, absorbance and optical band gap were determined by UV–Vis spectroscopy. Optical band gap for PTNZO nanocomposites were 2.72 eV, 2.34 eV, and 2.45 eV, respectively, with increasing RF power. For NZO thin films, this value is 3.12 eV. The optical band gaps calculated from the absorption and transmittance spectra obtained using UV–visible spectroscopy had a good compatibility with those of the optical band spectra calculated from the PL spectra. The tetragonal wurtzite structure of the NZO thin films was examined by SEM analysis. The grain size of NZO nanostructure was found to be approximately 59 nm.
AtıfScopus9WoS9OpenAlex9İncele - MakaleAçık Erişim2015Scopus SJRQ2Genotoxic and antigenotoxic potentials of two Usnea species
Ceker, Selcuk; Orhan, Furkan; Kizil, Hamit Emre; Alpsoy, Lokman; Gulluce, Medine; Aslan, Ali; Agar, Guleray
For ages, lichens have long been investigated popularly for biological roles, mainly antitumor, antimicrobial and antioxidant activities. Many positive results were obtained in these previous research. Thus, in this study, we aimed to determine whether extracts of Usnea articulata (UAE) and Usnea filipendula (UFE) possessing a protection against aflatoxin B1(AFB1)-induced genotoxic and oxidative damage. The results of our studies showed that 5 μM concentrations of AFB1increased the frequencies of sister chromatid exchange (SCE) and the level of malondialdehyde (MDA) and decreased the activities of superoxide dismutase (SOD), glutathione (GSH) and glutathione peroxidase (GPx). However, when 5, 10 and 20 µg/mL concentrations of UAE and UFE was added to AFB1, the frequencies of SCE and MDA level were decreased and SOD, GSH and GPx level were increased. The Ames (Salmonella typhimurium TA1535, TA1537) and WP2 (Escherichia coli) test systems carried out evinced that UAE and UFE possess any mutagenicity, but have antimutagenic effects. Consequently, the results of this experiment have clearly shown that UAE and UFE have strong antioxidative and antigenotoxic effects that are associated with its antioxidant nature. A detailed study can be performed to determine the antioxidant properties of each compound that will extend the use of lichen extracts in food and pharmacy industries.
AtıfScopus16WoS13OpenAlex14İncele - MakaleAçık Erişim2017Scopus SJRQ2Highly Enantioselective Production of Chiral Secondary Alcohols with Candida zeylanoides as a New Whole Cell Biocatalyst
Şahin, Engin; Dertli, Enes
The increasing demand for biocatalysts in synthesizing enantiomerically pure chiral alcohols results from the outstanding characteristics of biocatalysts in reaction, economic, and ecological issues. Herein, fifteen yeast strains belonging to three food originated yeast species Candida zeylanoides, Pichia fermentans, and Saccharomyces uvarum were tested for their capability for asymmetric reduction of acetophenone to 1-phenylethanol as biocatalysts. Of these strains, C. zeylanoides P1 showed an effective asymmetric reduction ability. Under optimized conditions, substituted acetophenones were converted to corresponding optically active secondary alcohols in up to 99% enantiomeric excess and at high yields. The preparative scale asymmetric bioreduction of 4-nitroacetophenone (1m) by C. zeylanoides P1 gave (S)-1-(4-nitrophenyl)ethanol (2m) with 89% yield and > 99% enantiomeric excess. Compound 2m has been obtained in an enantiomerically pure and inexpensive form. Additionally, these results indicate that C. zeylanoides P1 is a promising biocatalyst for the synthesis of chiral alcohols in industry.
AtıfScopus32WoS30İncele - MakaleAçık Erişim2016Scopus SJRQ1Heavily carbon doped GaAs nanocrystalline thin film deposited by thermionic vacuum arc method
Pat, Suat; Korkmaz, Şadan; Özen, Soner; Şenay, Volkan
In this paper, we introduced a new different thin film deposition method for heavily carbon doped GaAs. Used method is thermionic vacuum arc (TVA) and first used for the carbon doping process. The method is very fast deposition process for the other growth method such as metal organic chemical vapor deposition, molecular beam epitaxy, molecular organic molecular beam epitaxy. The smallest grain size of GaAs and doped GaAs were obtained by carbon doping process. Mean crystalline size and height of crystalline size were found to be 3.4 nm and 4 nm, respectively. Crystal direction was found to be (022) plane and (024) plane for the sample at 45.322° and 75.060°, respectively. The production process and obtained results show that used methods is very simple, low cost, eco friendly and very fast method for the carbon doped GaAs.
AtıfScopus9WoS9OpenAlex10İncele - BildiriAçık Erişim2016The effects of fuel type in synthesis of NiFe2O4 nanoparticles by microwave assisted combustion method
Karakaş, Zeynep Karcioǧlu; Boncukçuoǧlu, Recep; Karakaş, Ibrahim H.
In this study, it was investigated the effects of the used fuels on structural, morphological and magnetic properties of nanoparticles in nanoparticle synthesis with microwave assisted combustion method with an important method in quick, simple and low cost at synthesis of the nanoparticles. In this aim, glycine, urea and citric acid were used as fuel, respectively. The synthesised nanoparticles were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), Brunauer-Emmet-Teller surface area (BET), and vibrating sample magnetometry (VSM) techniques. We observed that fuel type is quite effective on magnetic properties and surface properties of the nanoparticles. X-ray difractograms of the obtained nanoparticles were compared with standard powder diffraction cards of NiFe2O4 (JCPDS Card Number 54-0964). The results demonstrated that difractograms are fully compatible with standard reflection peaks. According to the results of the XRD analysis, the highest crystallinity was observed at nanoparticles synthesized with glycine. The results demonstrated that the nanoparticles prepared with urea has the highest surface area. The micrographs of SEM showed that all of the nanoparticles have nano-crystalline behaviour and particles indication cubic shape. VSM analysis demonstrated that the type of fuel used for synthesis is highly effective a parameter on magnetic properties of nanoparticles.
AtıfScopus22WoS15OpenAlex18İncele - MakaleYalnız künye2013Scopus SJRQ2Analysis of trusses by total potential optimization method coupled with harmony search
Toklu, Yusuf Cengiz; Bekdaş, Gebrail; Temur, Rasim
Current methods of analysis of trusses depend on matrix formulations based on equilibrium equations which are in fact derived from energy principles, and compatibility conditions. Recently it has been shown that the minimum energy principle, by itself, in its pure and unmodified form, can well be exploited to analyze structures when coupled with an optimization algorithm, specifically with a meta-heuristic algorithm. The resulting technique that can be called Total Potential Optimization using Meta-heuristic Algorithms (TPO/MA) has already been applied to analyses of linear and nonlinear plane trusses successfully as coupled with simulated annealing and local search algorithms. In this study the technique is applied to both 2-dimensional and 3-dimensional trusses emphasizing robustness, reliability and accuracy. The trials have shown that the technique is robust in two senses: all runs result in answers, and all answers are acceptable as to the reliability and accuracy within the prescribed limits. It has also been shown that Harmony Search presents itself as an appropriate algorithm for the purpose.
AtıfScopus33WoS26OpenAlex26İncele - MakaleAçık Erişim2013Scopus SJRQ3Existence of solutions for an elliptic equation with nonstandard growth
Avci, M.; Mashiyev, R. Ayazoglu; Cekic, B.
This paper deals with the existence of solutions for some elliptic equations with nonstandard growth under zero Dirichlet boundary condition. Using a direct variational method and the theory of the variable exponent Sobolev spaces, we set some conditions that ensures the existence of nontrivial weak solutions.
AtıfScopus2OpenAlex2İncele
